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Instant Omni Plus 18L vs Mueller 4 Slice Toaster Oven Side-by-Side Comparison

Alan Nguyen
Reviewer
Nguyen Ntk
Visual Specialist
Updated
Tested Using Methodology v1.0
Updated Apr 3, 2023
Tested Using Methodology v1.0
Updated Apr 3, 2023
The front of a closed stainless steel Instant Omni Plus 18L 10-in-1 Countertop Convection Air Fryer Toaster Oven.
The front of a closed stainless steel Mueller MT-175 4-Slice Countertop Toaster Oven on a white background.

Our Verdict

8.6
Overall Score
  • Performance (50%)
    8.1/10
  • Design (25%)
    9.7/10
  • Usability (25%)
    8.4/10
6.1
Overall Score
  • Performance (50%)
    7.0/10
  • Design (25%)
    5.3/10
  • Usability (25%)
    5.2/10

Between the Instant Omni Plus 18L Air Fryer Toaster Oven and the Mueller 4 Slice Toaster Oven (MT-175), the first one is without a doubt the winner. Nonetheless, they still bring up interesting points of comparison as our best air fryer toaster oven and our best value small toaster oven respectively.

Design and usability-wise, the Mueller doesn’t offer much besides its detachable crumb tray for cleaning the inside. Meanwhile, the Instant has an LCD touchscreen with smart programs, audio cues, toggles, and cooking presets. The oven’s also equipped with a slide-out crumb tray, interior light, and tray-level indicators on the glass door.

Even though the Mueller couldn’t compete with a true powerhouse like the Omni Plus 18L in terms of performance, it still put up a good fight, especially for a small unit.

The Mueller was able to keep up with the Omni Plus in toasting bread, which was great. However, even though its results in baking pizza and roasting whole chicken were good, the Instant’s were exceptional.

Most importantly, the Mueller still has the common weakness in baking fries like many same-sized units whereas this test was the one where the Omni Plus excelled, even among all of our best picks.

Excellent Air Frying Capabilities

Instant Omni Plus 18L Performance

Mueller 4-Slice Toaster Oven Performance: Good Heat Distribution
8.1
Performance Scores
  • Toast (40%)7.3/10
  • Pizza (25%)8.6/10
  • Whole Roasted Chicken (25%)8.4/10
  • Baked French Fries (10%)9.3/10
7.0
Performance Scores
  • Toast (40%)7.5/10
  • Pizza (25%)7.6/10
  • Whole Roasted Chicken (25%)7.0/10
  • Baked French Fries (10%)3.6/10
7.3

Toast

7.5
From left to right, 24 pieces of toast for the top and bottom of three toast levels including lighter, medium, and darker.
On the left: Level 1; In the middle: Level 2; On the right: Level 3
From left to right, 24 pieces of toast for the top and bottom of three toast levels including lighter, medium, and darker.
The top and bottom of the best four pieces of toast from the Instant Omni Plus 18L 10-in-1 Air Fryer Toaster Oven.
On the left are the top and bottom of four pieces of toast from the first batch, and on the right are from the second batch.
Taste: 8
50% * 8 = 4.0
Even Surface Color: 6
20% * 6 = 1.2
Consecutive Usability: 7
30% * 7 = 2.1
  • Function: Toast
  • Number Of Slices: 4
  • Toast Level: 2/5
  • Cooking Time: 5m 25s
  • Second Batch: 4m 1s
  • Convection: No

Using the steps of our Toast test, we determined that level 2—5 minutes 25 seconds on the timer—was the best option scoring a 7.3/10. In comparison, the level 1 and 3 had a more uneven while being lighter and darker surface color respectively.

The Toast Level 2 of the Instant Omni Plus 18L produced four pieces with an 85% even golden brown color. Since the fan couldn’t be deployed, the toast had some darker spots and lighter areas resulting in a 6/10.

The first batch of toast was nicely crispy while still soft and moist inside and we gave it an 8/10 for taste. Our head chef Tuyet Pham determined it would be excellent with omelet and eggs benedict but not so good for sandwiches or soup.

This is one of the few ovens with a smart program that automatically deducts time to reach certain temperatures when the oven’s already hot. Thus, the surface color of the toasts was quite consistent throughout multiple batches. In addition, due to its extra crispiness, the second batch was determined to be good enough for soup.

If you want the second batch to be similar to the first, remember to lower it by one level. Overall, the score for consecutive usability was 7/10.

Mueller 4 Slice Toaster Oven Toast Test
From left to right, 24 pieces of toast for the top and bottom of three toast levels including lighter, medium, and darker.
The top and bottom of the best four pieces of toast from the stainless steel Mueller MT-175 4-Slice Countertop Toaster Oven.
On the left are the top and bottom of four pieces of toast from the first batch, and on the right are from the second batch.
Taste: 8
50% * 8 = 4.0
Even Surface Color: 7
20% * 7 = 1.4
Consecutive Usability: 7
30% * 7 = 2.1
  • Function: Toast
  • Number Of Slices: 4
  • Toast Level: ⅓ to Dark
  • Cooking Time: 4m
  • Second Batch: 4m
  • Convection: No

For our Toast test, we started off by trying the Medium Toast setting which was around 3 minutes 5 seconds on the timer. The four pieces of bread on the upper tray level came out only lightly toasted on top except for one golden brown piece. We then cranked it up to the Dark Toast setting—around 4 minutes 50 seconds on the timer—which, unfortunately, burnt the toast a bit.

Finally, we opted for the middle ground which was 4 minutes on the timer—⅓ of the rotation from Medium to Dark. This setting was tricky to get right on the time dial, so we used an external timer. It gave us the best possible toast results from this oven scoring a 7.5/10 in total.

After 4 minutes of toasting, the four pieces of toast had pretty good surface color. However, the colors varied from light golden to golden brown on both the top and the bottom, so we could only give a 7/10.

Luckily, the varied colors partially meant varied textures which were all good and deserving an 8/10. The golden brown areas had a more crispy outside while the light golden areas had a softer inside. Our head chef Tuyet Pham determined that it would go great with omelets, eggs benedict, and sandwiches but not so much with soup.

After taking out the first batch, we immediately put four more pieces inside to test the oven’s consecutive usability which ended up at 7/10. Also under the identical toasting time, the four pieces of bread became brown with an increased evenness from the first batch. While the color was a bit darker than ideal, the extra crispiness made the second batch more suitable for soups.

8.6

Pizza

7.6
A toaster oven baked 9-inch thick-crust meat pizza with cheese, onions, and green bell peppers on top inside a baking pan.
A toaster oven baked 9-inch thick-crust meat pizza with cheese, onions, and green bell peppers on top inside a baking pan.
The cross-section of a toaster oven baked pizza slice showing the crust. In the background is a pizza inside a baking tray.
Two hands break apart a slice of pizza with melty cheese, meat, and green bell peppers on top baked using a toaster oven.
Cooking Time: 10
20% * 10 = 2.0
Crust: 8
20% * 8 = 1.6
Toppings: 8.2
30% * 8.2 = 2.5
Taste: 8.5
30% * 8.5 = 2.5
  • Function: Bake
  • Temperature: 450°F
  • Cooking Time: 3m 50s
  • Convection: High

The Instant Omni Plus, having a very strong convection system, did not seem ideal for baking a 9-inch thick-crust meat pizza resulting in an 8.6/10.

A cooking time of only 3m 50s was extremely fast compared to the recommended 10 minutes on the label. After comparing it to other toaster ovens in our Pizza test, it was more than enough for a 10/10.

The crust, although golden brown, was a little soft with some lighter and darker areas due to the short cooking time plus strong fan. It got an 8/10.

The entire surface was a little too dry due to all the convection. In addition, while the cheese was nicely melted, caramelization wasn’t even due to the short cooking time. Thus, the final score for the toppings was 8.2/10.

Our chef gave the pizza an 8.5/10 for taste.

Mueller 4 Slice Toaster Oven Pizza Test
 Mueller 4 Slice Toaster Oven PizzaA toaster oven baked 9-inch thick-crust meat pizza with cheese, onions, and green bell peppers on top inside a baking pan.
Two slices of oven baked 9-inch thick-crust meat pizza with cheese, onions, and green bell peppers on top of one another.
Two hands break apart a slice of pizza with cheese, meat, onions, and green bell peppers on top baked using a toaster oven.
Cooking Time: 6
20% * 6 = 1.2
Crust: 8
20% * 8 = 1.6
Toppings: 8
30% * 8 = 2.4
Taste: 8
30% * 8 = 2.4
  • Function: Toast
  • Temperature: 450°F
  • Cooking Time: 9m
  • Convection: No

For its low power draw, the Mueller did pretty well in our Pizza test with a score of 7.6/10.

The oven took 9 minutes to bake a 9-inch thick-crust meat pizza which was slightly faster than the label’s recommended 10 minutes. However, compared to our tested toaster ovens, it could only be a 6/10.

The crust had a golden color all the way through and the inside was still moist. If only the crust was a bit more crispy, it would’ve gotten higher than an 8/10.

The toppings were also caramelized quite evenly from the meat and veggies to the cheese, worthy of another 8/10. The cheese was nicely melted but the areas closer to the back of the cooking chamber were more caramelized compared to the rest.

With both the crust and the toppings being 8/10, our chef had no reason to give the pizza one final 8/10 for taste.

8.4

Whole Roasted Chicken

7.0
A whole roasted rotisserie chicken using a toaster oven on an enamel baking pan on a white background.
A whole roasted rotisserie chicken using a toaster oven on an enamel baking pan on a white background.
A tray of whole toaster oven roasted chicken. The thermometer has two probes inside the chicken and displays 178°F and 190°F.
Seven pieces of a carved chicken including a carcass, two breasts, two wings, and two thighs on an enamel baking pan.
The close-up of a pulled-apart roasted chicken thigh. In the background is the rest of the roasted chicken on a tray.
Cooking Time: 9
20% * 9 = 1.8
Skin: 9.8
20% * 9.8 = 2.0
Doneness: 9
20% * 9 = 1.8
Taste: 7
40% * 7 = 2.8
  • Function: Roast
  • Temperature: 350°F
  • Cooking Time: 50 minutes
  • Convection: Yes

Following our Whole Roasted Chicken test, we chose a 3 lb chicken and it fit without a problem scoring an 8.4/10.

However, cleaning up was a big hassle as there wasn’t enough space below to use the drip pan. Worse still, during cooking fat splashed everywhere inside the oven causing the heating elements to smoke.

The roasting time was 50 minutes which was shorter than average and worthy of a 9/10.

The rotisserie kit and high convection together produced perfectly golden brown crispy skin deserving a 9.8/10. One thing to note is that due to the meat being considerably moist, the skin lost its crispiness in a relatively short time span.

The smooth rotation and high convection also allowed the whole chicken to be thoroughly cooked without any pink spots in just 50 minutes. The internal temperature was only a little higher than the USDA recommended 165°F-180°F at 178-190°F, so it got a 9/10.

The meat was almost fall-off-the-bone. Unfortunately, with it being so moist—to the point of softening the skin, our chef could only give it a 7 for taste.

Mueller 4 Slice Toaster Oven Whole Roasted Chicken Test
A whole roasted chicken using the Mueller MT-175 Toaster Oven backside up on a silver baking pan on a white background.
A whole roasted chicken using the Mueller MT-175 Toaster Oven belly up on a silver baking pan on a white background.
A tray of whole toaster oven roasted chicken. The thermometer has two probes inside the chicken and displays 185°F and 192°F.
Eight pieces of a carved chicken including two carcass halves, two breasts, two wings, and two thighs on a baking pan.
Two hands pulling apart a roasted chicken thigh. In the white background is the rest of the roasted chicken on a baking pan.
Cooking Time: 6
20% * 6 = 1.2
Skin: 5.5
20% * 5.5 = 1.1
Doneness: 8.7
20% * 8.7 = 1.7
Taste: 7.5
40% * 7.5 = 3.0
  • Function: Toast
  • Temperature: 350°F
  • Cooking Time: 1h 20m
  • Convection: No

The Mueller could barely fit a 3 lb chicken for our Whole Roasted Chicken test. Nonetheless, the result was quite decent at 7/10 in total. If you were to purchase this oven and use it to roast a whole chicken, we recommend cutting it open or chopping it into pieces beforehand.

We first placed the chicken backside down on the baking pan. When we slid the pan in, the top of the chicken breast grazed the upper heating element’s guard and was seared.

After the first 40 minutes, we flipped the chicken to find out that parts of the skin on the back got stuck to the baking pan. Then, when we reinsert the pan, the same problem with the breast happened to the back. Luckily, they weren’t burnt.

However, even after 1 hour and 20 minutes, most of the chicken skin still hasn’t reached a desirable color. The chicken, for the most part, looked like it was steamed and not roasted, so we gave the skin a 5.5/10.

Nonetheless, our chef decided to stop the roasting as the color wouldn’t improve anyway and to avoid overcooking the meat. This cooking time was the equivalent of a 6/10 according to our data.

With such a long cooking time, the meat had no pink spots. However, the chicken’s internal temperature was 185°F-192°F, higher than the USDA recommended 165°F-180°F. Thus, we gave it an 8.7/ for doneness.

While not the most appetizing looking, the meat was very juicy. That, combined with the slight caramelization on the skin, was enough for a 7.5/10 for taste from our chef.

9.3

Baked French Fries

3.6
Pieces of baked french fries using a toaster oven inside an air fryer basket on a grey background.
Pieces of baked french fries using a toaster oven inside an air fryer basket on a grey background.
A close-up of pieces of baked french fries using a toaster oven inside an air fryer basket on a grey background.
Ten pieces of broken-up baked french fries are stacked on top of pieces of whole fries inside an air fryer basket.
Cooking Time: 9
20% * 9 = 1.8
Color: 9.8
20% * 9.8 = 2.0
Texture: 9.8
20% * 9.8 = 2.0
Taste: 9
40% * 9 = 3.6
  • Function: Air Fry
  • Temperature: 400°F.
  • Cooking Time: 15m
  • Convection: High

The Instant Omni Plus was excellent at baking 12 oz of french fries with a score of 9.3/10.

After performing our Baked French Fries test on different toaster ovens, we came to the conclusion that the ideal cooking time for baked french fries was 15 minutes. However, it wasn’t the fastest one on our list so it scored a 9/10.

The strong convection combined with the air fryer basket produced evenly golden fries worthy of a 9.8/10 for color.

What helped the color also baked perfectly crispy fries while retaining a nice amount of moisture. This earned the oven another 9.8/10 for the texture of baked french fries.

Our chef gave the fries a 9/10 for taste.

Mueller 4 Slice Toaster Oven Baked French Fries Test
Mueller 4 Slice Toaster Oven Baked French FriesPieces of baked french fries using the Mueller MT-175 Toaster Oven on a grooved silver baking pan on a white background.
A close-up of pieces of baked french fries using the Mueller MT-175 Toaster Oven on a baking pan on a white background.
Ten pieces of broken-up baked french fries are stacked on top of pieces of whole fries on a grooved silver baking pan.
Cooking Time: 0
20% * 0 = 0.0
Color: 4.5
20% * 4.5 = 0.9
Texture: 4.5
20% * 4.5 = 0.9
Taste: 4.5
40% * 4.5 = 1.8
  • Function: Toast
  • Temperature: 400°F
  • Cooking Time: 27 m
  • Convection: No

Our Baked French Fries test brought out the Mueller’s weakness of not being able to maintain a high temperature due to its low power draw. Its even heat distribution couldn’t help much if the temperature wasn’t high enough, so the final score was 3.6/10.

We stopped the baking after 27 minutes as the fries weren’t getting any more colors. This, nonetheless, was over our time limit of 25 minutes, so it was a 0/10.

The fries had no significant color change and barely enough for a 4.5/10. We ended up with 12 oz of frozen fries that were more similar to being dried in an oven than being baked, so we gave them another 4.5/10 for texture.

Fortunately, the fries were cooked through and not soggy, so our chef could give them a 4.5/10 for taste and not a zero.

Modern Technology

Instant Pot Omni Plus Toaster Oven Design Review

Stainless Steel Mueller 4-Slice Toaster Oven Design Review: Standard
9.7
design Scores
  • Exterior (25%)9.5/10
  • Interior (30%)9.5/10
  • Build Quality (50%)9.0/10
5.3
design Scores
  • Exterior (20%)5.0/10
  • Interior (30%)1.0/10
  • Build Quality (50%)8.0/10

In the Instant Pot Omni Plus 18L Box

In the Mueller MT-175 Small Toaster Oven Box
An oven rack, air fryer basket, rotisserie kit, lifter, the Instant Omni Plus 18L, user manual, box, and enamel baking pan.
  • Model: 140-4002-01
  • Warranty: 1 year (US and Canada only)
  • User Manual
  • Baking Rack
  • Baking Pan
  • Rotisserie Kit and Lifter
  • Air Fryer Basket

Besides keeping all the accessories in place, the packaging also has interesting illustrations for the key information on the Instant Omni Plus 18L. You can quickly access the download page for the Instant Pot App thanks to the QR code on the package and the user manual.

Their website provides the full manual, how-to videos, FAQs, and more. You’ll also need to go there to register your product and activate your warranty.

A box, the Mueller MT-175 4-Slice Toaster Oven, a recipe booklet, a baking pan, an oven rack, a user manual, and a brochure.
  • Model: MT-175
  • Warranty: 1 year
  • User Manual
  • Baking Rack
  • Baking Pan

The Mueller toaster oven came in a basic packaging and positioned with two foam pads. The included accessories were simply duct-taped to the oven. Inside the box are also a user manual and a simple recipe booklet.

9.5

Exterior

5.0
A closed front of the Instant Omni Plus 18L 10-in-1 Air Fryer Toaster Oven with exterior measurements on a white background.
A closed front of the Instant Omni Plus 18L 10-in-1 Air Fryer Toaster Oven with exterior measurements on a white background.
The front of a closed Instant Omni Plus 18L 10-in-1 Toaster Oven has a control panel and the right has ventilation holes.
The back and left sides of the Instant Omni Plus 18L have air ventilation holes. The back has a power cord and two buffers.
The top of the stainless steel Instant Omni Plus 18L 10-in-1 Air Fryer Toaster Oven on a grey background.
On a grey background, the bottom of the stainless steel Instant Omni Plus 18L 10-in-1 Air Fryer Toaster Oven has two stands.
  • Weight:
    25.4 oz (721 g)
  • Length:
    16.5" (42.0 cm)
  • Width:
    15.8" (40.0 cm)
  • Height:
    13.9" (35.3 cm)
  • Material:
    Stainless steel
  • Color:
    Silver
  • Door Handle:
    cool-touch
  • Tray Indicators:
    Yes
  • Crumb Tray:
    Yes

An example of the Instant Omni Plus 18L’s clever design is the slide-out crumb tray not to mention its two strong base stands as well as air ventilation on two sides and the back. For safety, it has two buffers on the back to prevent the oven from sitting too close to the wall and a cool-touch door handle.

To accommodate its many cooking functions, there are tray-level indicators on the glass door. Our measurements of the oven’s footprint of 16.54" x 15.75" x 13.90" were quite different from the manufacturer’s 12" x 12" x 13.89" in terms of length and width.

We could explain that the difference in width was because we also took the dial and the back buffers into account but not the difference in length. Nonetheless, we didn’t find this to be a problem.

A closed front of the stainless steel Mueller MT-175 4-Slice Toaster Oven with exterior measurements on a white background.
A closed front of the stainless steel Mueller MT-175 4-Slice Toaster Oven with exterior measurements on a white background.
Mueller 4 Slice Toaster Oven ExteriorThe front of a closed stainless steel Mueller MT-175 4-Slice Toaster Oven has a control panel and the right has holes.
The back and left sides of the Instant Omni Plus 18L have air ventilation holes. The back has a power cord and two buffers.
The top, front, and right sides of the Black+Decker TO1760SS 4-Slice Natural Convection Toaster Oven on a white background.
On a white background, the bottom of the Mueller MT-175 Toaster Oven has a detachable crumb tray, four stands, and holes.
The detached crumb tray of the stainless steel Black+Decker TO1760SS 4-Slice Countertop Toaster Oven on a white background.
  • Weight:
    9.0 lbs (4.1 kg)
  • Length:
    15.0" (38.0 cm)
  • Width:
    11.6" (29.5 cm)
  • Height:
    8.9" (22.5 cm)
  • Material:
    Stainless steel
  • Color:
    Gray
  • Door Handle:
    Cool-touch
  • Tray Indicators:
    No
  • Crumb Tray:
    Detachable

As simple as it is, the Mueller has all the standard exterior features of a small toaster oven but also something more. The bottom of the oven acts as a detachable crumb tray which not only makes it easy to remove the falling bits and crumbs but also to clean the entire interior.

The oven has a cool-touch door handle and back buffers to prevent it from being too close to the wall. Unfortunately, it has no cord storage or carrying handles.

Our measurements of the oven’s footprint were 14.96" x 11.61" x 8.86" which pretty much coincided with the manufacturer’s 14.84" x 11.85" x 8.86". However, the weight of the oven by itself was already 9 lbs whereas the label said the entire box was 7.63 lbs.

Control Panel

Control Panel of the Small Mueller MT-175
The black touchscreen LCD of the Instant Omni Plus 18L Air Fryer Toaster Oven has 15 features and a master-control knob.
  • Type:
    black LCD digital touchscreen + one master-control knob
  • Temperature:
    150°F - 450°F
  • Timer:
    1 - 60 minutes
  • Indicator Light:
    Yes
  • Status Bar:
    No
  • Light Toggle:
    Yes
  • Convection Toggle:
    Yes
  • Rotation Toggle:
    Yes
  • Automatic Preheat:
    Yes
  • Audio Cues:
    Yes

This oven has a black LCD digital touchscreen and one master-control knob. The display includes the cooking status bar, functions, and toggles for Light, Convection, and Rotation. Besides the automatic oven preheat feature, it features an audio cue to turn food halfway through the input cooking time.

Audio cues include the beeps when you plug in the oven, select a function as well as adjust time and temperature, and when the oven finishes cooking. According to some reviews we’ve seen, they can be a bit loud, especially for households with children and/or pets. However, they can be turned off by pressing and holding the control knobs for 5 seconds until the screen displays S OFF.

The control panel of the Black+Decker TO1760SS 4-Slice Toaster Oven has 3 control knobs for temperature, function, and timer.
  • Type:
    3 control knobs
  • Temperature:
    150°F - 450°F
  • Timer:
    1 minute - 30 minutes + stay-on
  • Indicator Light:
    Yes
  • Status Bar:
    No
  • Light Toggle:
    No
  • Convection Toggle:
    No
  • Rotation Toggle:
    No
  • Automatic Preheat:
    No
  • Audio Cues:
    No

The Mueller has a basic analog control panel with three dials for temperature, function, and time. The time dial has a stay-on setting to help with its short range, similar to many other small toaster ovens. Interestingly, while the max temperature setting was 450°F, we actually recorded the internal temperature of the oven reaching 500°F on the said setting.

Cooking Functions

  • Air fry (180°F - 450°F)
  • Broil (350°F - 450°F)
  • Bake (180°F - 450°F)
  • Roast (180°F - 450°F)
  • Dehydrate (85°F - 175°F)
  • Reheat (120°F - 360°F)
  • Warm (170°F - 300°F)
  • Toast (level 1-5)

Even though there’s no Rotisserie function, the oven comes with a tailored rotisserie kit and a Rotation Toggle. Besides making dried fruits, herbs, and meat jerky, the Dehydrate function is also ideal for proofing bread dough at 85°F and Low Convect.

The function dial of the Black+Decker TO1760SS 4-Slice Toaster Oven has 3 cooking functions including Bake, Broil, and Toast.
  • Toast
  • Bake
  • Broil
  • Keep warm

Different from most other toaster ovens, the Mueller’s Bake function only uses the lower heating elements as opposed to lower and upper. The Broil function still uses only the upper heating elements.

The Toast function is where both the lower and upper heating elements work. Nonetheless, the oven still provides all the basic functions for its intended purposes.

9.5

Interior

1.0
The Instant Omni Plus 18L’s cooking chamber has 2 bottom heating elements, 3 guide rails, a rotisserie socket and bracket.
The Instant Omni Plus 18L’s cooking chamber has 2 bottom heating elements, 3 guide rails, a rotisserie socket and bracket.
The 2 bottom quartz heating elements of the Instant Omni Plus 18L 10-in-1 Air Fryer Toaster Oven have guards.
The cooking chamber ceiling of the Instant Omni Plus 18L Toaster Oven has two quartz and one swirl nichrome heating element.
The cooking chamber’s right wall of the Instant Omni Plus 18L has four guide rails, a rotisserie socket, and a shining light.
  • Heating Elements:
    4 quartz and 1 nichrome
  • Convection Fan:
    Yes
  • Lighting:
    Yes
  • Tray Levels:
    4
  • Rotisserie:
    Yes
  • Safety Hook:
    No

The Instant Omni Plus has four golden quartz heating elements. These pipes use infrared light to cook, which produces more heat and also cools down faster.

They are also easier to clean and more energy-efficient but don’t last as long in terms of durability. However, if grease splashes onto the heating elements while cooking, it’ll leave permanent stains.

Featuring safety guards, the heating elements are kept out of direct contact with baking pans and trays. The oven even includes a coil nichrome heating element at the top, specifically for broiling.

To top it off, this oven has a powerful and not noisy convection system as an interior light. In addition to 4 tray levels, you can make use of the baking rack with its rack-up and down positions.

Mueller 4 Slice Toaster Oven InteriorThe Mueller MT-175 4-Slice Toaster Oven’s cooking chamber has 2 quartz heating elements with guards and 2 guide rails.
Mueller 4 Slice Toaster Oven InteriorThe Mueller MT-175 4-Slice Toaster Oven’s cooking chamber has 2 quartz heating elements with guards and 2 guide rails.
The Mueller MT-175 Oven has 1 bottom heating element with a guard and 2 guide rails on its right cooking chamber wall.
  • Heating Elements:
    2 quartz
  • Convection Fan:
    No
  • Lighting:
    No
  • Tray Levels:
    2
  • Rotisserie:
    No
  • Safety Hook:
    No

Similar to many other small toaster ovens, including the Comfee CFO-BB101, the Mueller lacks a convection fan and an interior light. In addition, it only has two heating elements which can usually lead to uneven heat distribution compared to four or more heating elements.

These heating elements are made of quartz which uses infrared light to cook foods faster than the more common nichrome counterparts. Quartz heating elements also cool down faster, are more energy-efficient and easier to clean but not as durable.

However, if grease splashes onto the heating elements while cooking, it’ll leave permanent stains. This is why they usually have guards which this oven also has.

Capacity of the Instant Pot Omni Plus 18L

Capacity of the Mueller 4-Slice Toaster Oven
An opened front of the Instant Omni Plus 18L 10-in-1 Air Fryer Toaster Oven with interior measurements on a white background.
  • Length:
    13.8" (35.0 cm)
  • Width:
    12.6" (32.0 cm)
  • Height:
    8.7" (22.0 cm)

The Instant Omni Plus can comfortably fit a 12-inch pizza or a 4-pound chicken which is true to its description. However, it can’t quite fit 6 slices of toast. Moreover, when roasting only a 3-pound whole chicken with the rotisserie kit, there wasn’t enough space to fit a baking pan below. This wasn’t the case with a larger unit like the Cosori CO130-AO.

We measured the cooking chamber’s volume to be roughly 24.6 liters—a lot different from the manufacturer’s provided capacity of 18 liters. However, this could be because we measured from the cooking chamber’s walls to walls whereas the manufacturer stopped before reaching the heating elements.

An opened front of the stainless steel Mueller MT-175 4-Slice Toaster Oven with interior measurements on a white background.
  • Length:
    10.6" (27.0 cm)
  • Width:
    9.8" (25.0 cm)
  • Height:
    7.5" (19.0 cm)

We could fit four slices of toast, a 9-inch pizza but we could barely fit a 3 lb chicken inside the Mueller, unlike the same-sized Breville BOV450XL. We measured the cooking chamber volume to be around 12.81 liters, slightly different than the manufacturer’s provided capacity of 11.67 liters. However, it could just be a difference in measuring standards.

Power Cord

A three-pronged plug power cord. In the background is the Instant Omni Plus 18L 10-in-1 Air Fryer Toaster Oven.
  • Length:
    2.8 ft (0.9 m)
  • Type:
    3-prong plug
  • Power:
    1800 W
  • Rated Output:
    120 V ~ 60 Hz

The power cord is roughly 33.46"—more than long enough for household use. However, the cord can’t fully wrap around the two back stands as they are too high up.

A two-pronged plug power cord. In the background is the stainless steel Mueller MT-175 4-Slice Countertop Toaster Oven.
  • Length:
    30.7" (78.0 cm)
  • Type:
    2-prong plug
  • Power:
    1100 W
  • Rated Output:
    120 V ~ 60 Hz

The power cord is 30.7 inches long, suitable for household use. Unfortunately, the oven doesn’t have any storage space for it.

Baking Rack

Accessories

Baking Rack
A stainless steel baking rack of the Instant Omni Plus 18L 10-in-1 Air Fryer Toaster Oven on a grey background.
  • Length:
    12.4" (31.5 cm)
  • Width:
    11.4" (29.0 cm)
  • Height:
    0.9" (2.4 cm)
  • Material:
    Stainless steel
  • Dishwasher Safe:
    Yes

The rack fits perfectly with the guide which helps prevent accidents when placing your food in the oven.

A stainless steel baking rack of the Mueller MT-175 4-Slice Countertop Toaster Oven on a white background.
  • Length:
    10.5" (26.7 cm)
  • Width:
    8.8" (22.4 cm)
  • Height:
    0.5" (1.3 cm)
  • Material:
    Stainless steel
  • Dishwasher Safe:
    Yes

The two sides of the baking rack have slight curves upward at an angle to keep the baking pan in place. It fits perfectly with the guide to help prevent accidents when placing your food in the oven.

Baking Pan

Accessories

Baking Pan
An enamel baking pan of the stainless steel Instant Omni Plus 18L 10-in-1 Air Fryer Toaster Oven on a grey background.
  • Length:
    13.8" (35.0 cm)
  • Width:
    12.4" (31.5 cm)
  • Height:
    1.8" (4.6 cm)
  • Material:
    Stainless steel
  • Dishwasher Safe:
    Yes

Thanks to its perfect size, the baking pan does a great job of catching the meat juice and drippings from the air fryer basket. Thus, it helps prevent making a mess and avoid the danger of fire from dirty heating elements. Keep in mind that the dishwasher can damage the enamel coating.

A grooved silver baking pan of the stainless steel Mueller MT-175 4-Slice Countertop Toaster Oven on a white background.
  • Length:
    10.2" (25.8 cm)
  • Width:
    7.9" (20.0 cm)
  • Height:
    0.6" (1.5 cm)
  • Material:
    Stainless steel
  • Dishwasher Safe:
    Yes

The baking pan doesn’t fit into the guide rails and has to on top of the rack. This may prevent the full use of the oven’s capacity and lead to some inconveniences during cooking.

On the bright side, the pan has ridges and grooves to give your food attractive roasting marks and catch the dripping better. It has a coating but is not completely non-stick so you may need to watch out for some stubborn stains after a hefty roast.

Rotisserie Kit and Lifter

Accessories

A rotisserie kit and lifter of the stainless steel Instant Omni Plus 18L 10-in-1 Air Fryer Toaster Oven on a grey background.
  • Length:
    13.4" (34.0 cm)
  • Width:
    11.4" (29.0 cm)
  • Height:
    0.9" (2.4 cm)
  • Material:
    Stainless steel
  • Dishwasher Safe:
    Yes

The rotisserie kit does a perfect job of securing a chicken thanks to the 4-pronged forks with adjustable angles.

The structure of the forks isn’t very strong so parts can get bended although not by much.

Air Fryer Basket

Accessories

A stainless steel air fryer basket of the Instant Omni Plus 18L 10-in-1 Air Fryer Toaster Oven on a grey background.
  • Length:
    14.6" (37.0 cm)
  • Width:
    11.0" (27.9 cm)
  • Height:
    2.0" (5.1 cm)
  • Material:
    Stainless steel
  • Dishwasher Safe:
    Yes

The air fryer basket has a good elevation to help with heat circulation around the bottom of the food.

9.0

Build Quality

8.0
The front of an opened Instant Omni Plus 18L with a rack, a baking pan, an air fryer basket, a lifter, and a rotisserie kit.
The front of an opened Instant Omni Plus 18L with a rack, a baking pan, an air fryer basket, a lifter, and a rotisserie kit.
An oxidized slide-out crumb tray of the Instant Omni Plus 18L 10-in-1 Air Fryer Toaster Oven on a grey background.

The Instant Omni Plus 18L is a well-built and intricate piece of equipment, to say the least. It provides a helpful cooking status bar, smart programs, and automatic features. The oven does consume a lot of electricity so make sure your outlet can provide and handle 1800 W.

The meticulous design shows in the bottom tray, safeguards for heating elements, and cooling fan for its mainboard. However, the bottom tray can easily slide out if you tilt the oven. Also, during our roasting of a whole chicken, the hot drippings created some oxidation on the crumb tray.

The front of an opened stainless steel Mueller MT-175 4-Slice Countertop Toaster Oven with an oven rack and baking pan.

For a simple small toaster oven, build quality is all about how durable it is and if it works properly. The Mueller accomplishes that with a sturdy stainless steel casing and smooth-turning dials.

Not Yet Technological Perfection

Instant Omni Plus 18L Usability

Muller 4-Slice Toaster Oven Usability: Easy but Not Convenient to Use
8.4
usability Scores
  • User Control (30%)9.9/10
  • Ease of Use (50%)8.0/10
  • Cleanability (20%)7.0/10
5.2
usability Scores
  • User Control (30%)6.0/10
  • Ease of Use (50%)4.0/10
  • Cleanability (20%)7.0/10
9.9

User Control

6.0

The Instant Omni Plus 18L has 8 settings to choose from but can serve more than 10 functions. Although the LCD display could be improved with better contrast, it’s not a big problem.

The master-control knob can be confusing for first-timers but it should take little effort to get familiarized with it. The temperature can be adjusted in 1°F increments by turning the knob slowly and in 10°F increments by turning the knob fast. Also, the timer is specified by the minute.

If you want to readjust the setting during cooking, simply tap the feature and adjust it with the knob. Don’t tap Cancel as it will reset your inputs and repeat the automatic preheating.

The convection setting is applicable to almost all except for toast. One thing to note from the manual is that most recipes recommend reducing the temperature by 25°F when convection is on.

The convection fan speeds can toggle between high and low which is not very common for ovens, especially at the same price range. The two exceptions are Air Fry which always uses High Convect and Warm using Low Convect.

Even though the Mueller only has three simple control dials, there are a few things to keep in mind. For the timer knob, when setting it to less than 10 minutes, always rotate past 10 minutes and then rotate back to the desired time.

It’s always tricky to precisely adjust time and temperature for an analog-control toaster oven and this one is no different. Nonetheless, you can use an external timer and an oven thermometer to get more accurate readings.

If you frequently use the stay-on feature, you can turn off the oven by rotating the function dial to Off instead of the timer.

8.0

Ease of Use

4.0

When you adjust temperature and time for a function, the Instant Omni Plus saves your setting for next time use. After the oven finishes cooking, it will beep and automatically switch to Keep Warm mode until the display shows End.

After a period of no interaction, the digital display will show the word OFF similar to when you’ve just plugged it in. You’ll then need to push the knob once to turn it on. It’s advised to unplug the oven after you finish using it.

The light automatically turns off after 30 seconds of no interaction and turns on 30 seconds before finishing cooking. Opening the oven door pauses the cooking but the light stays on for another 30 seconds. Closing the oven door resumes the cooking but it will go into stand-by mode resetting all inputs after 5m30s.

Taking the rotisserie kit out of the oven can be a bit tricky even with the lifter. However, with a bit of practice, it’ll be no problem at all. The oven has good heat insulation, so the casing doesn’t get too hot to the touch at 350°F and 400°F but be careful at 450°F.

What’s convenient about 100% analog toaster ovens is that it’s very simple to adjust time and temperature during cooking. When the timer runs out, a bell will sound and the oven will shut off. Afterward, you can freely leave it plugged in and not worry about power consumption as it has no digital display.

The door can open at any angle < 50° to let food cool down inside the oven. However, keep in mind that opening the door doesn’t stop the oven. The exterior shell isn’t very thick, so it gets hot to the touch quite quickly during cooking.

7.0

Cleanability

7.0
Grease on the slide-out crumb tray inside the cooking chamber of the Instant Omni Plus 18L 10-in-1 Air Fryer Toaster Oven.
Grease on the slide-out crumb tray inside the cooking chamber of the Instant Omni Plus 18L 10-in-1 Air Fryer Toaster Oven.
The cleaned cooking chamber floor and 2 bottom heating elements of the Instant Omni Plus 18L 10-in-1 Air Fryer Toaster Oven.
Brushing the stained upper quartz heating elements of the Instant Omni Plus 18L 10-in-1 Air Fryer Toaster Oven.

We cleaned the Instant Omni Plus 18L following our toaster oven cleaning guide. Despite having an internal and external coating, it still wasn’t easy to clean due to some very tricky nooks and crannies. The small gaps between the heating elements and internal walls didn’t help either.

Most of the mess came from the considerable fat splatter from roasting a whole chicken. It left difficult stains on the heating elements and their safeguards which were already tricky to clean.

With the removable oven-bottom tray, cleaning up the crumbs was extremely easy but we still had to tilt the oven to get all of the crumbs out. On the bright side, having thought it would be difficult to clean caramelized bits of food from the air fryer basket due to the fishnet design, we were happy to find this wasn’t the case.

Mueller 4 Slice Toaster Oven CleanabilityPermanent stains on the left cooking chamber’s ceiling and the upper heating element’s guard of the Mueller MT-175 Oven.
Mueller 4 Slice Toaster Oven CleanabilityPermanent stains on the left cooking chamber’s ceiling and the upper heating element’s guard of the Mueller MT-175 Oven.
Permanent stains on the right cooking chamber’s ceiling and the upper heating element’s guard of the Mueller MT-175 Oven.
The cleaned grooved silver baking pan of the stainless steel Mueller MT-175 4-Slice Countertop Toaster Oven.

We clean the stainless steel exterior with no problem. However, after the chicken test, there were burnt bits stuck to the upper heating element’s guard and grease on the cooking chamber’s ceiling. There was ample space between the ceiling and the upper heating element, so we proceed to try every cleaning method possible.

Unfortunately, we could only scrub off the bits. Due to the interior not having a non-stick coating, there were some permanent stains on the cooking chamber’s ceiling and the upper heating element’s guard.

Luckily, the heating element itself was intact. Also, we were able to remove the stubborn stains on the baking pan by brushing them with a paste of baking soda and water.