Ninja Double Stack XL review: does the tall air fryer beat the wide one?

Forty-one and a half centimetres. That's how much worktop the Ninja AF400UK took off me when I tested it in July, and it's how the bread bin ended up living on top of the fridge. I said at the time it was worth it. I still think so. But every time I made a sandwich standing on tiptoe, a little voice asked if there was a better way.

The Ninja Double Stack XL is Ninja's answer to that voice. Same 9.5 litres, same two drawers, but one on top of the other instead of side by side. It's 28 cm wide. On paper, that's 13.5 cm of worktop back.

Paper doesn't have two lads on their summer holidays, though. So from 11 August to 7 September, the Double Stack moved in next to the AF400UK and fed Kai, who's 12, Freddie, who's 9, Lee, me and a rotating cast of Kai's mates. I logged 47 cooks, six of them on both fryers at once.

Which Double Stack this is

Ninja sells two stacked fryers in the UK and the names are close. The one I tested is the SL400UK, the Double Stack XL: 9.5 litres split between a pair of 4.75 litre drawers, grey with long silver handles. There's also a white version, coded SL400UKWH. Its little brother is the SL300UK, the plain Double Stack at 7.6 litres, which I'll come back to under alternatives.

The trick of the stacked design is inside each drawer. You get a crisper plate for the bottom and a stainless steel rack that sits above it, so each drawer has two levels. Two drawers, two racks, four layers. Ninja says it'll cook a 1.4 kg chicken in each drawer. Hold on to that number, because I tested it.

The numbers before the chips

How I tested it

Every kitchen gadget we try gets the same kit, and the full method sits on our how we test page. A plug-through meter behind the fryer counting every watt. A decibel meter at arm's length plus a bit. My probe thermometer in anything that used to have feathers. And the fridge whiteboard, which Freddie now treats as his personal newspaper.

The school holidays made it a harder test than July: lunch as well as tea, and Kai's friends turning up at twelve with a football and no warning. 19 of the 47 cooks used the racks.

For the six head-to-heads, same food and weight went in both fryers, started and pulled together. Freddie did the blind tasting from plates marked A and B. He took the job very seriously and wore his swimming goggles for it, for reasons he wouldn't explain.

Chips, and a slightly slower drawer

Start where every air fryer review should: a 900 g bag of frozen chips, a single drawer, 200°C on Air Fry, straight from cold. The AF400UK had them golden in 19 minutes. The Double Stack needed 22, and here's the thing I didn't expect: at the halfway shake, the chips at the back of the drawer were noticeably darker than the ones at the front.

It makes sense once you know the design. On the stacked Ninja the heat comes from the back of each drawer rather than straight down from the top, so the back row gets it first. The fix is simple. Shake at the halfway point and again at three quarters, and push the pale ones to the back. Do that and Freddie couldn't tell A from B. He scored them 8 and 8, and then asked if he could have both plates.

Proper chips, Maris Pipers cut thick with a spoonful of oil, took 28 minutes at 200°C against 26 in the wide fryer, and were gone before I'd found the vinegar. Max Crisp at 240°C was brilliant on frozen waffles and nuggets. For anything fresh, I stayed at 200°C or lower.

Four layers of tea: the trick the wide one can't do

This is where the Double Stack earned its place. The racks sound like a gimmick until you have four lads in your kitchen after a kickabout.

The best tea of the month went like this. Top drawer: eight chipolatas on the rack, potato waffles underneath. Bottom drawer: chicken drumsticks on the plate, corn on the cob on the rack above. Different times, different heats, Sync pressed, and one beep 24 minutes later. Five hungry people fed from one appliance, and the oven stayed cold on a warm August night.

Two things I learned the hard way. Fat drips down. Sausages on the rack above waffles means waffles cooked in a bit of sausage fat, and nobody here complained. Bacon above hash browns is a different story, because by the end the hash browns were soggy on top. Put the dry stuff on top and the drippy stuff underneath.

The rack layer also cooks a bit faster, so the quick things go up top.

"It's like a vending machine for tea. You pull a drawer and there's something different in every shelf." Kai, week two, with a corn cob in each hand

The whole chicken test, and where tall means shallow

Here's the catch in going upwards. To stack two drawers in 38.5 cm, each one has to be shallow. Wide and long, but not tall. Ninja says 1.4 kg of chicken per drawer, and that's exactly where it stops.

My first Sunday I bought a 1.6 kg bird, because that's what feeds us. It went in the bottom drawer. The drawer wouldn't close. The breast was touching the top. I tried it upside down, I tried it at an angle, and Lee suggested "sitting on it", which I did not. The chicken went in the AF400UK instead, which took it without a fuss.

The next Sunday I bought a 1.4 kg bird on purpose. It fitted with about a finger's width to spare, cooked on Roast at 180°C, and after 55 minutes the probe showed 75°C deep in the thigh. Golden skin, juicy breast, and roasties ready at the same beep in the top drawer. Lovely, but a 1.4 kg chicken with two growing lads means nobody gets seconds.

Same story with baking. A sponge in a shallow tin rose towards the element and caught on top. For cakes, the oven is still my friend.

Living with a tall fryer

The space. It sits in the bread bin's old spot, and the bread bin has come down off the fridge, to Freddie's delight. 28 cm really is a different life on a short worktop. It also fits under our wall cupboards, which start 45 cm above the worktop, but I pulled it forward to cook every time. It breathes out warm air at the back, and I don't want the underside of a cupboard steamed for a month.

The top drawer. On a tall fryer the top drawer handle is roughly at the height of a 9-year-old's face. When it opens, a puff of hot air comes out right there. After one yelp from Freddie, who was fine but offended, the house rule became: grown-ups open the top drawer. It's worth thinking about if you have little ones.

The weight and the beep. At 10.3 kg, moving it to wipe behind is a bend-your-knees job. And it has the same loud Ninja beep with no volume control, so Lee's naps after early shifts remain at risk.

Washing up: drawers easy, racks less so

The drawers have a non-stick ceramic coating and wiped out in two or three minutes each, even after drumsticks. After 47 cooks, not a scratch, because the no-metal rule from July still stands.

The racks are the weak spot. Melted cheese from a toastie night welded itself into the joins of the thin steel wires. They're dishwasher safe, and in the end that's where they went. If you hate washing up, you'll use the racks less than you think.

How loud, and how many pence a tea

Both drawers on, my meter read 58 dB at a metre, a touch more than the wide one's 56 dB. A fan whoosh, no whine.

For the sums I used 26.32p a unit, which is what Ofgem's cap allows on average for Direct Debit electricity between October and December 2026. Check your own bill, yours may be a little different.

So about 13p saved on a typical tea, the same saving as the wide Ninja. Five teas a week adds up to roughly £34 over a year. Lee has already worked out it's two and a half portions of fish and chips at Whitby, which is how he measures everything.

Double Stack XL or AF400UK: which should you buy?

I had both on the worktop for four weeks, so here's the straight answer. Freddie's blind tasting, six rounds, came out three to the wide one, two to the stack and one draw. That's a coin toss. Cooking quality is not the reason to choose.

Choose on your kitchen. Short worktop, lots of small things, kids who each want something different: the Double Stack. Room to spare, whole chickens every Sunday, no patience for washing racks: the wide one, which I reviewed in full in my Ninja Foodi MAX Dual Zone review.

Buy now or hold out for 27 November?

That's the date of Black Friday this year. Before you set a reminder, here's what the price has actually done, so you can tell a real deal from a relabelled one.

• List price: £269.99. Nobody should pay that, and hardly anyone does.
• Right now: £199.99 at Ninja, around £189 to £199 at Currys, AO and Very. PriceSpy's tracking shows a low of £182 and a high of £226 over the last three months.
• Past sales: Trusted Reviews reported it at £184.99 on Amazon during a Prime Day sale, £85 off. In Black Friday 2024, Very had it at £189.

So the "deal" price of about £185 to £199 is really its normal price now. My rule of thumb: under £180 is a genuinely good price, buy on the spot. £185 to £190 is fine if you need it now. Above £200, wait.

Would it make a good present?

For the right person, it's a brilliant one. Think of a couple in their first flat with a galley kitchen, or a parent who's just downsized and still cooks for the grandkids. It's a big box under the tree, and it gets used on Boxing Day, when everyone wants turkey sandwiches and chips.

It's a less good present for someone who roasts a big chicken every Sunday or bakes a lot. They'll bump into the shallow drawers within a fortnight.

Worth buying alongside it:

• Silicone-tipped tongs, because metal will scratch the coating. A few pounds from any supermarket.
• An oil sprayer, since a light mist is all chips need.
• Paper or silicone liners, but measure the drawer floor first. Many "Ninja-size" liners are made for the wide fryer and won't sit flat in this one.

Returns first. Ninja's own shop takes main units back free within 30 days. Order from any website and UK law (the Consumer Contracts Regulations) gives you a fortnight after it arrives to send it back for any reason. Lots of shops push their Christmas return dates into January, though every shop sets its own, so read the till receipt and get a gift receipt at the till. The 2-year guarantee only kicks in when the fryer is registered with Ninja, so pop the proof of purchase in with the card.

Right kitchen, wrong kitchen

Alternatives worth a look

Ninja Foodi MAX Dual Zone AF400UK, about £170 to £200. The wide one. Faster on chips, fits a 1.8 kg chicken, no racks to wash. Needs 41.5 cm of worktop.

Ninja Double Stack SL300UK, £199.99 at Ninja. The smaller stacked model at 7.6 litres, oddly listed at the same price as the XL right now. Only worth it if it's clearly cheaper elsewhere.

Ninja Foodi FlexDrawer AF500UK, £199 at Ninja. One big drawer with a removable divider. It swallows whole chickens and joints, and with the divider in you still get two separate cooks. It's wide, though, so it doesn't fix the worktop problem.

All our kitchen scores sit together in our reviews, if you want to compare.

After 28 days

The Double Stack is staying and the AF400UK has gone to Lee's sister, who has a bigger kitchen and three teenagers. That tells you where I landed. For our terraced kitchen, the space mattered more than the three minutes on chips or the chicken size.

The back row browns first, the racks are a chore, and a proper Sunday bird is off the menu. But on a holiday Wednesday, with four lads and a football in my kitchen, one tall grey box put four different things on the table at once. Freddie has retired the goggles. The bread bin is back where it belongs.

Your Ninja Double Stack XL questions, answered