What Are the Disadvantages of Ninja Air Fryers? 7 Things to Know

Ninja air fryers are popular for good reason. They can cook food quickly, use less oil than deep frying and make preparing smaller meals easier. But they aren't necessarily the right choice for every kitchen. Some models occupy a surprising amount of worktop space, others are noisy, and the biggest capacity doesn't always mean the most useful cooking area. There are also differences in cleaning, running costs and price that are worth understanding before spending your money.

We've compared three established Ninja models, checked the manufacturer's specifications and looked at independent testing to identify seven disadvantages that actually matter. If you decide a Ninja is right for you, our Ninja Kitchen voucher codes and offers page is worth checking before you buy.

Ninja Double Stack XL air fryer on a kitchen worktop with its lower cooking drawer open

1. Ninja Air Fryers Can Take Up More Space Than Expected

It's easy to look at the capacity of an air fryer and overlook its physical dimensions. The Ninja Foodi MAX Dual Zone AF400UK, for example, measures 41.5cm wide. That's quite a substantial appliance to keep permanently on a kitchen worktop, particularly when you also need room to pull out the drawers.

The Double Stack XL SL400UK tackles this problem by placing its two drawers vertically rather than side by side. At 28cm wide, it's 13.5cm narrower than the AF400UK. Sounds ideal for a smaller kitchen, doesn't it?

There is a catch. The Double Stack measures 47cm deep, compared with 27cm for the AF400UK, and it's also taller. It saves width but requires more depth, so it won't necessarily fit every kitchen better.

Ninja also specifies at least 15cm of space above and around the appliance for ventilation in the Double Stack instructions. That is particularly important if you have low kitchen cupboards.

Our advice: Measure the space where the air fryer will actually sit, including room for ventilation and drawer access. Don't choose the Double Stack simply because it's advertised as a space-saving model.

2. A Large Capacity Doesn't Always Mean More Cooking Flexibility

One of the more confusing things about shopping for Ninja air fryers is the way capacity is advertised.

The AF400UK offers 9.5 litres, but that capacity is divided between two separate 4.75-litre drawers. It's excellent for cooking two different foods at different temperatures. However, you cannot remove the middle section to create one large cooking space.

The FlexDrawer AF500UK works differently. It offers 10.4 litres with a removable divider, allowing you to switch between two separate cooking zones and one large MegaZone. That makes it more accommodating for certain larger dishes or roasting joints.

How Three Ninja Air Fryers Compare

Model	Capacity	Dimensions (H × W × D)	Main trade-off
Foodi MAX AF400UK	9.5L	32.5 × 41.5 × 27cm	Two fixed drawers; no single large cooking zone
FlexDrawer AF500UK	10.4L	Check exact unit dimensions before ordering	One large removable-divider drawer
Double Stack SL400UK	9.5L	38.5 × 28 × 47cm	Narrower but deeper and taller

Source: Ninja product specifications, checked November 2026. Dimensions refer to appliance measurements, not the additional clearance needed during operation. Some published AF500UK measurements differ, so check the current manufacturer listing and installation instructions before buying.

We think the important distinction is the shape of the cooking space rather than the number of litres alone. Two separate drawers can be useful for cooking chicken and vegetables independently, but a single large drawer might be better for a sizeable joint of meat.

Ninja Foodi FlexDrawer AF500UK air fryer displayed with roast meat and cooked dishes

3. Some Ninja Air Fryers Are Surprisingly Noisy

Air fryers rely on powerful fans to circulate hot air around the food, so some operational noise is unavoidable. However, not every model is equally quiet.

Consumer testing by Which? measured the Ninja AF400UK at 54.8 decibels, describing the noise as moderate and comparable to a refrigerator.

Meanwhile, Good Food's November 2026 air fryer review lists noise among the disadvantages of the Ninja Double Stack XL, despite awarding it an excellent overall rating.

Neither finding means these are excessively noisy appliances. But if your kitchen is open-plan and you regularly watch television or work nearby while cooking, it's worth taking into account.

4. Dishwasher-Safe Parts Still Need Looking After

One attraction of Ninja air fryers is that many removable cooking components are dishwasher safe. That certainly makes cleaning easier, but there's a small detail worth knowing.

Ninja's instructions for the AF500UK confirm that its drawer, divider and crisper plates can go in the dishwasher. However, the manufacturer recommends handwashing to help extend their life. The main electrical unit must never be immersed in water or placed in a dishwasher.

This is particularly relevant if you're planning to use your air fryer every day. Non-stick surfaces need care, and greasy food residue can become awkward to remove if left to build up.

Our advice: Don't assume dishwasher-safe means maintenance-free. Follow the instructions for your exact model, avoid unsuitable abrasive cleaning products and clean the removable cooking parts regularly.

5. A More Expensive Ninja Isn't Necessarily a Better Buy

Ninja's range includes relatively straightforward air fryers as well as larger machines with two cooking zones, removable dividers and additional functions. Those features are useful, but only if you actually need them.

As an indication of the price differences, Good Food's 9 November 2026 buying guide listed the simpler 7.6L Ninja AF200UK at £159.99, the 9.5L AF400UK at £230 and the 9.5L Double Stack XL at £269. These were advertised retailer prices, not a like-for-like quotation from one shop, and prices can change.

The gap between the AF400UK and Double Stack prices in that snapshot was £39. The Double Stack may justify the extra expense if its narrower layout solves a genuine space problem. But if you already have enough room for the AF400UK, the additional cost may not offer much practical benefit.

The same principle applies to paying extra for the FlexDrawer. Its removable divider is valuable if you frequently cook larger dishes that cannot fit inside a standard dual-drawer machine. If you mainly make chips, chicken portions and vegetables separately, two fixed drawers may already meet your needs.

Our view: Start with the meals you cook most often, then choose the drawer arrangement and features that suit them. Buying the most expensive Ninja simply because it has more functions is an easy way to spend more than necessary.

6. Electricity Savings Depend on What You're Cooking

Air fryers are often promoted as cheaper alternatives to conventional ovens. They certainly can be, particularly for smaller meals, but the saving depends on the food, cooking time and amount being prepared.

The AF400UK and Double Stack SL400UK both have a rated maximum power of 2,470 watts. That doesn't mean they continuously consume 2,470 watts throughout every cooking programme. Actual electricity use depends on how the appliance operates during the cooking cycle.

Good Food's 2026 testing calculated approximately 4.1p to run the Double Stack for ten minutes, using an electricity price of 22.36p per kWh. That figure is a useful measured reference, although your actual cost will depend on your tariff and how you use the appliance.

There's another consideration. Cooking two portions of food in an air fryer can be economical compared with heating a large oven. Cooking a substantial family meal in several separate batches may reduce that advantage, especially if your existing oven can cook everything together.

We wouldn't purchase a large Ninja on the assumption that it will automatically halve the household's electricity bills. The likely saving is much more specific: shorter cooking times and less electricity for certain meals.

7. An Air Fryer Still Won't Replace Every Oven Function

Modern Ninja air fryers are much more versatile than the early basket-style machines. The AF400UK has six cooking functions, including Bake, Roast and Dehydrate, while the FlexDrawer AF500UK adds a Prove function.

Even so, there are physical limitations. Large baking trays, oversized casserole dishes and some roasting joints simply won't fit inside particular drawer shapes. Cooking several foods for a large gathering can also be less straightforward than using the shelves of a conventional oven.

One particularly important point is that the AF400UK's two drawers remain separate even when both are set to the same cooking programme. They do not turn into one large oven cavity.

The FlexDrawer offers more flexibility for larger dishes because its divider can be removed, but it remains a countertop appliance with a much smaller cooking chamber than a full-size oven.

Our advice: Think of a Ninja air fryer as a useful additional cooking appliance rather than a guaranteed complete replacement for your oven.

Ninja Foodi MAX Dual Zone AF400UK air fryer on a kitchen counter with cooked salmon, vegetables and muffins

Which Ninja Air Fryer Drawbacks Matter Most to You?

After comparing the specifications and independent findings, we don't think there's one disadvantage that makes Ninja air fryers a poor purchase. The compromises simply affect households differently.

Your main concern	What we would recommend
Limited worktop width	Consider the Double Stack, but check depth, height and ventilation clearance carefully.
Cooking large joints	Look at the FlexDrawer and its removable divider rather than relying on capacity alone.
Cooking two foods separately	A conventional Dual Zone model may be sufficient without paying extra for a different design.
Small portions and occasional use	Compare smaller single-drawer models before purchasing a large family-sized appliance.
Sensitive to noise	Check independent noise testing for the specific model. Don't assume every Ninja operates at the same volume.

For us, the biggest potential mistake isn't choosing a Ninja air fryer. It's choosing the wrong Ninja air fryer. A large machine can be unnecessary for somebody living alone, while a dual-drawer model might frustrate someone who regularly cooks larger joints of meat.

If you've decided which model suits your kitchen, compare the final price rather than relying on the headline discount. Ninja's own promotions, retailer sale prices and available voucher offers can differ, and a promotional voucher won't necessarily apply to every appliance.

My Favourite Voucher Codes donates 20% of its monthly profits to charity, with the charities selected through our monthly poll.

Research and Sources

This article was updated on 10 November 2026 using published Ninja product specifications, manufacturer instructions and independent consumer testing. The product comparisons and buying recommendations are editorial analysis; we have not carried out hands-on testing of these appliances ourselves. Prices and availability may change.

Written by Julian House 10th November 2026