Best air fryers UK 2026: what up to 75% less than an oven measures, and why the watts decide and litres do not

Jump to what you came for: what the energy percentage is measured against, why the watts decide and the litres do not, the watts per litre calculator, the browning advice and what the window is for, the eleven at a glance or the eleven, one by one.

The first thing a British buyer meets in this category is a percentage, and it is worth reading it slowly because it is doing a lot of work. On 16 September 2026 the first organic result for this search said, on its own shop: Cooking with a Ninja air fryer can cost up to 75% less than an oven, costing as little as 8p for 15 minutes, with a dagger on the first claim and four asterisks on the second. The fourth result said use up to 65% less energy than a conventional oven, and its footnote reads, in full: Versus using a conventional Energy Class A oven. The eighth result said air fryers are generally more energy-efficient than traditional ovens with no figure and no footnote at all.

None of those is a lie. They are all comparisons against an oven, which is a different appliance doing a different job, and every one of them carries an up to. What none of them gives you is the number that would let you check any of it, or compare two air fryers with each other: the wattage. Ninja publishes litres on every product on that page and the watts on none of them. Tefal lists capacities from 4.5 to 15 litres and no wattage. Morphy Richards publishes neither.

There is one thing you can do with the claim, and it is the sort of arithmetic this guide is for. Run the 8p for 15 minutes backwards at the Ofgem price cap of 26.32p per kWh for 1 October to 31 December 2026 and it implies an appliance drawing about 1.2 kilowatts. That derivation only holds if that 8p was worked out at the same unit rate; if it was not, the implied wattage moves with it. Which is exactly the point: the watts should have been on the page instead of the percentage.

An air fryer is a fan with a heating element inside. The litres tell you how much fits; the watts tell you how much heat there is to fill it. The same tray of chips in a bigger space, heated by the same element, takes longer. That is not an opinion, it is a division, and it is the one thing this whole category leaves out.

Of the 53 air fryer listings in the catalogue m8d tracks, counted on 28 August 2026, 49 declare the litres and only 15 declare the watts. Ten name the basket material and five give the temperature range. The British shop pages read today match that pattern exactly: litres on every product, wattage on none.

So the question to take into a shop is not how many litres, it is how many watts per litre, and it is a division you can do on any listing in front of you, whatever the badge on it.

The calculator below takes the two figures from whatever listing you are looking at, including one that is not in this guide, and does the division in front of you. It also turns the watts into kilowatt hours for a normal batch and for the same dish in an oven with its preheat, so you can multiply by your own unit rate instead of ours.

And it has a result that matters more than the others: the watts are not declared. That is not a hole in the tool, it is the most common case in the catalogue and the honest answer is that with that listing the sum cannot be done. A tool that only worked with the good listings would hide the problem.

The expensive mistake in this category is not buying cheap: it is buying big. Every extra litre is space the same element has to heat, so unless the wattage goes up with the size, a bigger machine cooks the same tray more slowly. The arithmetic is on this page rather than in a warning: the four litre machine here runs at 475 watts per litre and the twelve litre one at 217, and the twelve litre one is the most powerful of the eleven.

As a working rule from the machines that do declare both figures: two litres is one portion, four litres is one or two people, six to six and a half is the size most people buy and covers two or three, eight is three or four in one batch, and twelve is a machine you should only buy if you genuinely cook for a crowd. And a twin basket of nine litres is two of four and a half, not one of nine, which matters the day you want to put a whole chicken in. If there are two of you we would not go past six and a half litres, and the reason is in the chart below rather than in taste: the twelve litre machine on this page is the most powerful of the eleven at 2,600 watts and the slowest per tray of all of them at 217 watts per litre.

Chips are what an air fryer gets bought for, and there is official advice in this country about cooking starchy foods that almost no buying guide in this category mentions. Government guidance on acrylamide, the substance that forms when starchy foods such as potatoes and bread are cooked above 120C, tells consumers to aim for a golden yellow colour or lighter when frying, baking, toasting or roasting starchy foods. Not a temperature, not a time: a colour.

That is the argument for the window, and it turns a styling feature into a functional one. A colour judgement means looking, and in an air fryer looking means pulling the drawer out, which lets the hot air go and makes the machine climb back to temperature. A window lets you judge the colour without paying for it in heat. It is also why the glass-fronted machines that have taken over the British listings this year are not just a look: what changes is that you can see the food while it is cooking.

The same guidance has a second piece of advice that has changed and that most people still repeat the old version of. Keeping raw potatoes in the fridge used to be advised against for this reason; the current position is that home storage of potatoes in the fridge does not materially increase their acrylamide forming potential compared with a cool, dark cupboard, so you can choose either and cut waste. If you have been keeping potatoes out of the fridge because of something you read years ago, that is the current advice, with its source below.

Ordered by what each listing declares, not by what its name promises. The columns are exactly the four figures that decide, and the empty cells are the finding: not stated is literal, and it is the most common entry in this table.