The Ninja Double Stack puts two air-fryer drawers one above the other instead of side by side. That makes it a potentially useful choice when counter width is scarce, but it trades width for height and does not add cooking capacity over an equivalent side-by-side model. This is a launch-event preview, not a full independent performance test.
What makes the Ninja Double Stack different?
The Double Stack is a dual-zone air fryer with two vertically arranged drawers and a side-mounted control panel. Each drawer has its own crisper plate and multi-layer rack. Ninja sells two UK models: the 7.6-litre SL300, with two 3.8-litre drawers, and the 9.5-litre SL400, with two 4.75-litre drawers. The larger model is called the Ninja Double Stack XL 2-Drawer Air Fryer.
Both models offer Air Fry, Max Crisp, Bake, Roast, Reheat and Dehydrate functions. Their layout is the main innovation: the appliance changes where the cooking zones sit, rather than introducing a new kind of cooking technology. Ninja’s SL400 specifications and SL300 product page list the models’ functions and accessories.
Does stacking the drawers really save space?
It saves counter width, but the dimensions still matter. The SL400 is approximately 38.5cm high, 28cm wide and 47cm deep. The SL300 is approximately 38.5cm high, 28cm wide and 42cm deep. Ninja describes the SL400 as 30% slimmer than the AF400 and the SL300 as 25% slimmer than the AF300; those are manufacturer comparisons, not measurements of how much space every kitchen will save.
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#1 Best Overall
- SPACE SAVING DESIGN: Ninja’s stacked design lets you cook double the food in nearly half the space and still fits under standard cabinets. Plus, it’s 40% slimmer than your traditional 2-basket air fryers.
- DOUBLESTACK AIR FRYING TECHNOLOGY: Only Ninja’s stacked design has 2 independently controlled baskets so you can cook 4 foods at once.
- COOK 4 FOODS WITH STACKED MEAL RACKS: Includes 2 removable stacked meal racks allowing you to cook on 2 levels per basket. Superheated air surrounds both foods in each basket for an all-around crisp.
- SMART FINISH & MATCH COOK: Choose between the Smart Finish feature, which unlocks cooking 2 foods 2 ways that finish at the same time, and the Match Cook feature, which easily copies settings across zones for full 10-qt. capacity meals.
- XL FAMILY-SIZED CAPACITY: 10 QT capacity lets you cook two, 5-lb chickens at once and can feed up to 8 people.
Before buying, measure the appliance where it will actually operate—not just where it will be stored. Check the full depth, clearance above the machine, room to open and remove the upper drawer, and access to the side controls. Ninja’s SL400 support information says adequate clearance is required above and around the appliance for air circulation. A narrow counter is only an advantage if the height and access work in practice.
How much food fits, and what does “four layers” mean?
The SL300 holds 7.6 litres in total; Ninja positions it for up to six people. The SL400 holds 9.5 litres and is positioned for up to eight. Those household figures are manufacturer guidance, not a promise that a complete meal for that many people will fit in one batch. Usable cooking space depends on food size, shape and whether it needs to be spread out.
| Model | Total capacity | Capacity per drawer | Manufacturer positioning |
|---|---|---|---|
| SL300 | 7.6L | 2 × 3.8L | Up to six people |
| SL400 | 9.5L | 2 × 4.75L | Up to eight people |
Each drawer includes a crisper plate and a rack, so the two drawers can hold food across as many as four layers. But there are only two independently controlled cooking zones: food on a rack shares the settings of the drawer below it. Crowding or stacking food can also affect airflow and browning. Ninja recommends checking food and shaking or tossing it for the result you want; do not assume every layer will cook identically.
Rank #2
- SPACE SAVING DESIGN: Ninja’s stacked design lets you cook double the food in nearly half the space and still fits under standard cabinets. Plus, it’s 40% slimmer than your traditional 2-basket air fryers.
- DOUBLESTACK AIR FRYING TECHNOLOGY: Only Ninja’s stacked design has 2 independently controlled baskets so you can cook 4 foods at once.
- COOK 4 FOODS WITH STACKED MEAL RACKS: Includes 2 removable stacked meal racks allowing you to cook on 2 levels per basket. Superheated air surrounds both foods in each basket for an all-around crisp.
- SMART FINISH & MATCH COOK: Choose between the Smart Finish feature, which unlocks cooking 2 foods 2 ways that finish at the same time, and the Match Cook feature, which easily copies settings across zones for full 8-qt. capacity meals.
- FAMILY-SIZED CAPACITY: 8 QT capacity lets you cook 4 lbs of chicken wings at once and can feed up to 6 people.
The layout is most naturally suited to smaller pieces and separate meal components—such as fries and chicken pieces, or vegetables and fish—where the drawers can run as two zones. Wide steaks or chops, a large flat cake, a whole chicken, long items and foods that need a single uncrowded layer may be awkward. Capacity in litres does not tell you how well a particular shape will fit.
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| Model | Total capacity | Layout | Best fit |
|---|---|---|---|
| Double Stack SL400 | 9.5L | Two vertical drawers | Narrow counters and two simultaneous dishes |
| Foodi MAX Dual Zone AF400 | 9.5L | Two side-by-side drawers | Those who prefer same-level access and monitoring |
| Foodi MAX FlexDrawer AF500 | 10.4L | Two zones or one MegaZone | Large, flat or irregularly shaped food |
The SL400 and AF400 have the same nominal total capacity, divided into two 4.75-litre drawers. The difference is geometry and access, not extra volume. A side-by-side design may be easier when you want to inspect or shake both drawers at the same level; the Double Stack is the more compelling option if width is the constraint. There is no comparative cooking test here to establish that one cooks better.
The AF500 FlexDrawer can operate as two zones or as one larger MegaZone. Its 10.4-litre capacity and broad compartment make it a more natural option for a roast, whole fish, casserole-style food or traybake, provided you have the counter width. Ninja’s dual-zone comparison page outlines the range.
Rank #3
- SPACE SAVING DESIGN: Ninja’s stacked design lets you cook double the food in nearly half the space and still fits under standard cabinets. Plus, it’s 40% slimmer than your traditional 2-basket air fryers.
- SMART COOK SYSTEM: Achieve the perfect doneness, from rare to well-done, at the touch of a button with the integrated Foodi Smart Thermometer—no guesswork required.
- DOUBLESTACK AIR FRYING TECHNOLOGY: Only Ninja’s stacked design has 2 independently controlled baskets so you can cook 4 foods at once
- COOK 4 FOODS WITH STACKED MEAL RACKS: Includes 2 removable stacked meal racks allowing you to cook on 2 levels per basket. Superheated air surrounds both foods in each basket for an all-around crisp.
- SMART FINISH & MATCH COOK: Choose between the Smart Finish feature, which unlocks cooking 2 foods 2 ways that finish at the same time, and the Match Cook feature, which easily copies settings across zones for full 10-qt. capacity meals.
A smaller single-drawer air fryer is likely to be simpler and easier to store if you usually cook one portion at a time for one or two people. Paying for two zones makes more sense when simultaneous cooking is a regular need.
What the launch preview did—and did not—show
The article behind the “I tried” framing was published by T3 on February 5, 2024, after a SharkNinja EMEA launch event. Its writer saw a working demonstration, liked the vertical arrangement for smaller kitchens and said the food shown looked tasty and moist. That is a personal reaction to a demonstration, not a reproducible comparison with the AF400 or AF500. Read the original T3 preview.
The preview does not establish exact cooking performance, whether upper and lower drawers brown equally, energy use in a household, noise, long-term durability or how easy racks are to clean after greasy food. Those questions should not be answered by treating a launch demonstration as a full review.
Rank #4
- SMART FINISH & MATCH COOK: DualZone Technology allows you to choose between the Smart Finish feature, which unlocks cooking 2 foods 2 ways that finish at the same time, and the and a Match Cook button to easily copy settings across zones for full 8-qt capacity.
- 6-IN-1 FUNCTIONALITY: Includes 6 versatile cooking programs: Air Fry, Air Broil, Roast, Bake, Reheat, and Dehydrate. The baskets can be washed in the dishwasher or by hand.
- XL CAPACITY: The 8-quart air fryer capacity lets you fit mains and sides at the same time for making quick family meals, or up to 4 lbs. of French fries or chicken wings.
- SEPARATE HEATING ZONES: 2 independent 4-quart zones have their own cooking baskets, cyclonic fans, and rapid heaters.
- EASY CLEANING: Easy-to-clean baskets and dishwasher-safe crisper plates.
Practical compromises to consider
Height and drawer access
At about 38.5cm tall, the Double Stack may not suit a low cabinet or a spot where the upper drawer cannot be comfortably opened and removed. Measure with the appliance in its operating position, leaving the clearance Ninja requires.
Food shape and airflow
Racks add flexibility, not two extra independent zones. Small pieces with space around them are a more plausible use for stacked cooking than broad foods or a crowded layer. Be ready to check, toss or reposition food rather than expecting every level to behave the same way.
Cleaning and materials
Ninja lists the drawers and crisper plates as dishwasher-safe. Its support information identifies PTFE-coated drawers and non-stick aluminium crisper plates with a nano-ceramic coating; the exterior is BPA-free. The racks and the appliance body are not the same as those dishwasher-safe components, so check the care instructions and expect to remove grease from rack surfaces. Ninja’s support FAQ provides the coating and cleaning details.
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Best Value
- SMART FINISH with DualZone Technology: Sync both independent ovens to cook 2 meals, 2 different ways that finish at the same time.
- FLAVORSEAL TECHNOLOGY: Two separate ovens prevents smells from transferring between ovens, so your flavors stay totally separate.
- FLEXDOOR: Creates two separate ovens. Access just the top for quick meals and snacks, or open the full door so you can cook 2 meals, 2 ways on the top and bottom.
- 12-IN-1 FUNCTIONALITY: Includes 12 versatile cooking programs: Bake, Broil, Reheat, Keep Warm, Toast, Bagel, Air Fry, Conv.Bake, Pizza, Air Roast, Whole Roast, and Dehydrate.
- XL FAMILY-SIZED CAPACITY: Fits up to 6lbs of wings, 6 salmon filets, a 4.5-pound chicken, family size sheet pan meals, and up to 6 slices of bread.
Power and energy claims
Ninja lists rated power of 2,470W for both UK models. It also advertises energy savings of up to 55% for the SL400 and up to 60% for the SL300 compared with an oven. These are manufacturer claims based on specified foods and cooking conditions, not guaranteed savings for every meal or household. The UK product specifications are for 220–240V models; model numbers, voltage, warranty and availability can differ elsewhere.
Which Double Stack model makes sense?
- Choose the SL400 if you need the full 9.5-litre capacity and have a narrow counter but enough vertical clearance. Its capacity matches the AF400’s nominal total.
- Consider the SL300 if you want the stacked layout but 7.6 litres is sufficient for your household and typical batches.
- Choose a side-by-side model such as the AF400 if you have room for the width and prefer to access and monitor both drawers at the same level.
- Consider the AF500 FlexDrawer if one broad cooking zone for a large or irregular item matters more than a narrow footprint.
- Choose a smaller single-drawer model if simultaneous cooking is uncommon and you do not need family-scale capacity.
Price and availability in the UK
At the February 2024 launch preview, price and availability had not yet been announced. Later Ninja UK listings showed price signals around £199.99 for the SL300 and £229.99 to £269.99 for SL400 listings or variants; the AF400 appeared around £229.99 and the AF500 at £269.99 in comparison results. These are not verified live prices for October 2026, and offers, colours and stock can change. Check the official SL400 listing, official SL300 listing and Ninja offers page for current UK details. These figures and model specifications should not be assumed to apply to the US or other markets.
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