Why an air fryer isn't just a small oven
Both appliances cook with hot air, but an air fryer is forced convection taken to an extreme: a powerful fan drives air at high speed through a small, enclosed basket sitting right next to the food. A conventional oven heats a much larger, mostly still cavity — even with a fan-assisted setting, the air moves more slowly and has more space to fill. That difference in airflow speed and distance is what changes the numbers: the same displayed temperature transfers heat to the food's surface faster in an air fryer, so a recipe written for an oven will tend to brown or burn on the outside before the inside catches up if you use its numbers unchanged.
The rule of thumb — and where it comes from
We didn't invent a ratio for this tool. Two independent, citable sources — on opposite sides of the Atlantic and in different units — converge on almost the same adjustment. Cuisinart's own air fryer conversion chart tells cooks to reduce the oven temperature by about 25°F and the cooking time by about 20%. Arla UK's oven-to-air-fryer conversion guide, written for a Celsius-reading UK audience, gives the same time cut — about 20% — alongside a temperature reduction of 15–20°C.
Worth being precise about: 25°F and 20°C are not the same amount of temperature — a 25°F difference is roughly 14°C. These are two separately-rounded rules of thumb, one popularised for Fahrenheit kitchens and one for Celsius kitchens, not a single figure translated between units. So the tool applies whichever matches the unit you picked instead of forcing a false-precision conversion: °C subtracts (or adds back) 20°C, °F uses 25°F. Time works the same either way — multiplied by 0.8 going to the air fryer, divided by 0.8 (about 25% longer) coming back.
A worked example straight from Arla's own published chart: an oven recipe at 205°C for 15 minutes becomes roughly 190°C for about 12 minutes in the air fryer — a 15°C drop, within their 15–20°C range, and exactly 20% off the time. Run the same numbers through this tool and you'll get the same answer.
What this rule can't know about your appliance
A generic percentage has no idea what's in your kitchen. It doesn't know your appliance's wattage, whether it's a single basket, a dual-zone basket, or an oven-style unit with a much larger cavity, or how full the basket is on this particular batch — all factors that change real cook times far more than a flat 20% ever could. Our own comparison of official manufacturer charts found two air fryers, at the identical 180°C, needing 15 minutes and 40 minutes respectively for the same chicken breast — see why cook times vary so much between brands. No universal rule survives contact with a gap that size.
One trap is worth flagging on its own: frozen convenience food. Packet instructions for frozen fries, nuggets or fish fingers are written for a domestic oven — but plenty of brands now print air-fryer timings on the same box. Apply this reduction to numbers that are already air-fryer-adjusted and you double-count it, which undercooks the food. Convert theoven line, never the air fryer one.
When to use this, and when to use the real numbers instead
Reach for this converter when you've got an ordinary oven recipe — a bake, a traybake, a roast — and no air fryer version of it exists yet. It gives you a sensible number to start checking from, rather than guessing blind or leaving the food in for the oven's full time.
Reach for the cook time calculator instead whenever your exact appliance is in our database. A measurement sourced to a specific manual page, or tested by us directly, will always beat a rule averaged across every wattage and basket shape on the market — because it isn't averaged across anything. It's the number for your machine.
A few conversions this rule doesn't cover
"Is there a standard conversion for air fryer recipes?" This is about as close as it gets: the same adjustment, published separately by an appliance manufacturer and a food brand. But two related questions often hide behind that one, and this rule answers neither.
Converting a deep-fry recipe to an air fryer is a different problem, not a smaller version of this one. Deep frying submerges food in oil at a high, very stable temperature that transfers heat far faster than air ever can — an air fryer replaces that oil with fast-moving hot air and a light coating of it on the food's surface instead. You can't take a deep-fry oil temperature and subtract 20°C from it and expect a comparable result; the starting point should be closer to how you'd already air-fry that type of food (temperature-wise) than to the oil temperature the deep-fry recipe specifies.
Pressure-cooker air fryer lids — the kind that clip onto a multi-cooker — are still small forced-air chambers, so the same temperature and time reduction is a reasonable starting point for them too. The difference is usually capacity: these lids often cook in a shallower, wider pot than a dedicated air fryer basket, so a batch that's crowded may need a few extra minutes, or splitting into two batches, regardless of what the converted number says.
Four checks before you trust the number
- Check a few minutes before the converted time is up — both sources behind this rule say the same thing, and it costs nothing to open the basket early.
- Shake the basket or flip the food partway through if it benefits from even browning; an air fryer's airflow isn't perfectly uniform across the basket.
- For meat and poultry, don't trust the timer at all — check the internal temperature with a probe thermometer. The USDA safe-internal-temperature thresholds we show on every food page apply regardless of which appliance or converted time got you there.
- If this rule consistently burns or undercooks on your specific machine, that's a sign your air fryer runs hotter or cooler than the "average" the rule assumes — worth checking whether your model already has a sourced measurement on this site.