The packet gives you three oven settings and not a word about air frying. It is tempting to knock a few minutes off and hope for the best. A little adjustment often works, but the starting point matters: a tray of vegetables, a deep pie and a frozen chicken portion will not respond in quite the same way.
Use the food’s air-fryer instructions when available, alongside your appliance manual. For oven-only recipes, follow your model’s conversion advice. Manufacturer examples differ: Ninja’s AF180UK Bake instructions lower a conventional oven setting by 10°C, while Instant’s fresh-food guide lowers it by 20°C and cuts the time by 20–25%. These are starting estimates, not a guarantee that the centre is cooked.
Start with the packet, then your manual
If the packet lists an air-fryer method, use it. Check the suggested portion size as well as the temperature: instructions for half a bag are a poor guide to a drawer packed with the whole lot. Keep any directions about cooking from frozen, turning or removing packaging.
When there is no air-fryer method, look for a chart or conversion note in your appliance manual. Choose advice for the function you intend to use. A Bake instruction does not automatically apply to a fixed-temperature Max Crisp programme.
Why there is more than one conversion rule
Ninja’s AF180UK instructions give a 10°C reduction from a conventional oven recipe in the Bake section and tell you to check frequently. Instant’s published fresh-food method makes a different adjustment: 20°C lower and 20–25% less time. Neither example establishes a rule for every appliance.
Here is the arithmetic for Instant’s fresh-food method. Multiplying the oven time by 0.75–0.8 gives the shortened range. The table illustrates that calculation only; it does not supply cooking instructions for a particular food. Celsius and Fahrenheit settings below are rounded equivalents.
Smart tipWrite the original oven setting beside your first air-fryer attempt. Add the amount cooked, the setting you used and when it was ready. That note is more useful next time than a conversion percentage on its own.
Read the fan oven line carefully
A packet may show both conventional and fan oven settings. Before subtracting anything, identify which setting the conversion guidance refers to. Ninja’s example explicitly names a conventional oven. Do not take the lower fan setting and then apply a conventional-oven reduction as though they were the same starting temperature.
If the source only says “oven”, check the recipe notes. When the starting setting is unclear, an air-fryer recipe for the same food and a similar quantity is a better reference than stacking several guessed adjustments together.
Make the first batch easy to judge
Use a modest amount and leave space around larger pieces. Follow your manual on preheating, fit the appropriate basket or cooking dish and keep a note of the starting conditions. A smaller portion may brown sooner than the full oven recipe suggests.
Inspect the food before your estimated finish. Shake small pieces or turn larger ones where the method calls for it. If the surface is getting dark while the middle is still underdone, lower the setting and continue checking. Increasing the temperature to hurry the centre can simply burn the outside.
The timer tells you when to look. Before serving, check that food requiring thorough cooking is cooked through; use a clean food thermometer where appropriate. A crisp coating alone cannot tell you what is happening underneath.
Some oven dishes need a different approach
A deep casserole or large pie has a centre that takes time to heat. Changing the appliance does not make that depth disappear. A shallower suitable dish or smaller portion may help, but changing the dish also changes the recipe. Use a method written for that arrangement when possible.
For frozen food, keep the manufacturer’s cooking restrictions. Do not apply a fresh-food percentage to raw frozen meat or a product labelled for oven cooking only. If the packaging rules out air frying, use the stated method. Wet batter and dishes with lots of free liquid also need more thought than a time conversion.
Air fryers vary in power and basket design. Use these timings as a starting point and follow your manufacturer’s instructions where they differ.
Frequently asked questions
Do I always subtract 20°C for an air fryer?
No. That is one manufacturer’s suggested adjustment for fresh food. Use the advice for your model and function, and check which oven setting it starts from.
Can I use the same conversion for frozen food?
Do not assume so. Use the packet’s air-fryer method if supplied and retain its instructions about cooking from frozen. A fresh-food calculation is not a reliable substitute.
Should I shorten the time if I have already lowered the temperature?
Only as the chosen guidance suggests. Instant’s fresh-food method changes both, while the Ninja Bake example gives a temperature reduction and calls for frequent checks. Avoid combining parts of different rules.
What if the air fryer cannot reach the converted setting?
Use an appliance-specific recipe within your machine’s range, or cook the dish in the oven as directed. Selecting the nearest available setting does not guarantee the same result.
Sources and further reading
Safety, appliance and recipe guidance was checked against the following sources. Always follow the instructions for your own model.
