How the figure is calculated
Air fryers carry no energy label, so the only defensible figure is the manufacturer’s rated power: the heating element and fan at full tilt. We multiply that by the time you cook, by a duty cycle, and by your price per kWh. Once the basket reaches temperature the element switches on and off, so real use is below the rating; the duty cycle starts at 100 % and you can lower it.
No typical cooking time is published anywhere official, so there is no pre-filled time. Twenty minutes is a fair test for chips.
What drives the cost
Wattage and cooking time. A 2.1-quart Cosori Lite is 900 W, a dual-zone Ninja AF400UK 2,470 W with both drawers going. Preheating, opening the basket and cooking in batches all add minutes.
Worked example
US: the Cosori Pro LE 5.0-quart is rated 1,500 W, 27.47¢ an hour at 18.31¢/kWh. A 20-minute cook at full power costs 9.16¢; five of those a week is $23.87 a year.
GB: the Philips Airfryer 5000 Series XL HD9280 is rated 2,000 W, 52.64p an hour at 26.32p/kWh. Twenty minutes is 17.55p at full power, or 10.53p if the element is on 60 % of the time. The Ninja AF400UK at full power is 65.01p an hour.
Is it cheaper than the oven?
Usually, for small portions, because it heats a small box instead of a large one and cooks faster. For a full tray of food, type your oven’s wattage into the custom field and compare.
Questions
Why no air fryers from ENERGY STAR or the EU label?
Neither scheme covers air fryers, so we use manufacturer spec pages and say so.
Does preheating count?
Yes. Add the preheat minutes to your cooking time.
What duty cycle should I use?
We have no tested figure. Leave 100 % for the maximum, or lower it if you have measured your fryer with a plug-in meter.