If you’re a bill-paying adult living in the UK, the chances are you’re familiar with money-saving supremo Martin Lewis, whose cost-cutting advice has truly come to the fore in 2022 amid rising energy prices and general inflation-related badness.

For his latest trick, Lewis, founder of the Money Saving Expert website, has turned his attention to the kitchen in a bid to help you save money on everyday cooking and laundry tasks. Speaking on the latest episode of The Martin Lewis Podcast, he revealed a simple equation that should take the guesswork out of deciding which household appliances are the most efficient to use this winter, and help you work out whether appliances such as the best air fryers are saving you money.

“We know a kilowatt (kw) is 1,000w, which is how electricity tends to be priced [...] and you pay roughly 34p per kw per hour,” Lewis explained. “[So] the general equation is: find the wattage of an item, then work out how many kilowatts or what fraction of a kilowatt it’s using, then multiply that by 34p per hour of use.”

Lewis proved the value of the maths by using dehumidifiers as an example. Drying your clothes with a 200w dehumidifier – instead of a large standing dryer – could cost you as little as 7p an hour, he said, because 200w is a fifth of a kw (1,000w) and a fifth of 34p is 7p.

Lewis noted that the 7p figure doesn't take into account the initial cost of buying a dehumidifier, which can cost anywhere between £50 and £400, but the equation also applies to other household appliances like air fryers and heated airers (which should offer an answer to the question: do air fryers use a lot of electricity?).

You can find the best deals on a selection of air fryers, dehumidifiers and heated airers below.

For more appliance-related advice this winter, check out our explainer articles on the 6 common air fryer mistakes to avoid and the 9 things you need to know about air fryers