Air fryer conversion is the process of restating cooking instructions written for one appliance so they produce the same result in another. For a conventional oven recipe cooked in an air fryer, the standard conversion is to reduce the temperature by 25°F (15°C) and the cooking time by 20%.
This page defines air fryer conversion, explains the two adjustments it consists of, lists the conversion factor for every appliance pair, and sets out the conditions under which the standard rule stops holding.
What are the two adjustments in an air fryer conversion?
There are two, and they correct different things.
The temperature adjustment compensates for the surface effect. An air fryer moves air across food at high velocity, which strips away the thin layer of cooler, moisture-laden air that clings to food in a still oven. Without that insulating layer, heat reaches the surface faster, so the same dial setting browns and dries harder.
The time adjustment compensates for the bulk effect. Faster surface heat transfer creates a steeper thermal gradient into the food, so the centre reaches its target sooner.
Applying only one produces a predictable failure. Reduce the time alone and the surface overcooks; reduce the temperature alone and the food is underdone at the original time.
What is the conversion factor for each appliance?
There are six pairs in common use.
| From | Temperature change | Time factor |
|---|---|---|
| Conventional oven | −25°F / −15°C | × 0.8 |
| Convection or fan oven | −10°F / −5°C | × 0.9 |
| Toaster oven | −25°F / −15°C | × 0.8 |
| Microwave | No equivalent | × 3 (approximate) |
| Deep fryer | +25°F (15°C) above oil temperature | × 3 (approximate) |
| Grill or broil | Use maximum setting | × 1.5 |
Reversing a conversion uses the reciprocal of the factor, not the same percentage. The inverse of 0.8 is 1.25, which is why an air fryer recipe converted back to an oven gains 25% of its time rather than 20%.
Is an air fryer the same as a convection oven?
Mechanically they are the same category of appliance: a heating element and a fan. The differences are fan speed, which is roughly two to three times higher in an air fryer, and cavity volume, which is often a twentieth of an oven’s. Those two differences are the entire reason the convection conversion is small and the conventional oven conversion is large.
When does the standard conversion stop working?
In seven identified conditions. Each has a documented adjustment.
- Below 325°F (165°C) — the surface effect weakens; reduce by 15–20°F (-5°C) rather than 25°F (-5°C).
- Cakes and risen bakes — reduce time by 15% rather than 20%.
- Cookies — reduce temperature by 50°F (10°C) rather than 25°F (-5°C).
- A basket more than two-thirds full — add 15–20% back, or split the batch.
- Units under 1,400W — add roughly 10% to the time.
- Wet batters — cannot be converted at all; the coating drips through before it sets.
- Items over 4 lb (1.8 kg) — will not fit with air clearance; use an oven.
The full derivation of the rule and its limits is set out on the methodology page.
Why does air fryer conversion matter?
Because almost no recipe in circulation was written for an air fryer. Cookbooks, packaging, family recipes and the majority of online recipes assume a conventional oven, and using their figures unchanged in an air fryer produces food that is dark outside and underdone inside.
Related conversions and adjacent topics
Temperature and time convert together, never separately. The same rule set covers every appliance pair on this site, and the methodology page sets out where it comes from and the seven conditions under which it stops holding.
Every figure above is built into the oven to air fryer conversion calculator, which applies both adjustments together so you do not have to work them out separately.
Frequently asked questions
What is air fryer conversion?
The process of restating cooking instructions written for one appliance so they produce the same result in another — for an oven recipe, 25°F (-5°C) lower and 20% less time.
What is the basic oven to air fryer rule?
Reduce the temperature by 25°F (15°C) and multiply the cooking time by 0.8.
Does the rule work in reverse?
Yes, using the reciprocal: add 25°F (-5°C) and multiply the time by 1.25.
Is the conversion the same in Celsius?
Subtract 15°C rather than 25°F (15°C), and keep the same time factor. Work in the unit the recipe uses rather than converting between systems.