Do I actually need to preheat an air fryer?

About three minutes is enough, and it matters most for things that should sear on contact — a steak, a chop, anything breaded. For frozen food and slow-roasting vegetables you can skip it and simply add a couple of minutes, since the food spends the warm-up climbing anyway. The one case where preheating is worth insisting on is baked goods, where a cold start changes how the batter rises.

My recipe is already written for a fan oven. Do I still drop 25 °F?

No — halve it. A fan oven has already made part of the correction, so drop 15 °F instead of 25 °F and take roughly 12 percent off the time rather than 20 percent. Applying the full conventional adjustment twice is the most common reason converted recipes come out underdone, and it is easy to spot: the food is pale at the time the recipe said it would be finished.

Can I use foil or parchment in the basket?

Yes, with two conditions: never during the preheat, because loose paper will be lifted into the element, and never covering the perforations, because blocking the airflow turns the machine into a small bad oven. Cut the liner smaller than the basket floor and let the food weigh it down. For anything you want crisp underneath, skip the liner entirely — the holes are the point.

How to Convert Any Oven Recipe for an Air Fryer

Published 6/26/2026 · 7 min read · Everyday calculators

Marco Bianchi — Home, DIY & motoring writer at Allin

Renovation · Materials

Checked against 2 sources

View profile →

In short

From a conventional oven recipe, lower the temperature by 25 °F and cut the time by about 20 percent, then round the temperature to the nearest 5. From a fan or convection recipe the correction is lighter: 15 °F down and roughly 12 percent off, because that oven already moves hot air. The 20 percent is an average, and the food decides the real figure — reheated leftovers want 25 percent off, frozen food and general roasting 20 percent, vegetables 18 percent, chicken and fish 15 percent, and baked goods only 10 percent. Then account for the basket: a single uncrowded layer runs about 8 percent faster and a full basket about 15 percent slower. So a 400 °F, 25-minute tray of frozen fries becomes 375 °F for 20 minutes, with the first check at 12 minutes and a shake at 10.

A woman sliding a dish into an oven in a sunlit kitchen. — Anna Shvets · Pexels · Pexels

Drop 25 °F and cut the time by about a fifth — then adjust for what the food is and how full the basket is, because those two change the answer more than the rule does.

Why the rule is a temperature cut and not a time cut

An air fryer is a small convection oven with an aggressive fan. The chamber is a fraction of an oven's volume and the heating element sits inches from the food, so the air moves faster and the surface heat transfer is much higher for the same set temperature. The consequence is not that everything cooks faster uniformly — it is that the outside runs ahead of the inside. Cutting the temperature restores the balance; cutting only the time would leave you with something scorched outside and cool in the middle.

This also explains why the two adjustments are not independent. The temperature drop is a fixed physical correction — 25 °F from a still oven, 15 °F from one that already blows — while the time cut varies with how the heat has to travel through the food. Baked goods barely move, because a muffin's setting time is governed by the batter's interior, not its crust. Leftovers move most, because they only need to be warmed through.

Where the rule breaks: batter, liquid and volume

The conversion adjusts a recipe's settings; it cannot adjust its physics. A wet batter that would sit calmly on a baking sheet gets blown off the food by the fan, which is why breaded items need a dry, pressed coating and a spray of oil rather than a tempura-style dip. Anything with free liquid — a braise, a custard, a saucy casserole — is not an air fryer recipe at all, and no arithmetic makes it one.

Volume is the other hard limit. The basket of a typical domestic machine holds a fraction of a full oven tray, so a recipe for four portions frequently becomes two batches, and the conversion says nothing about that. Doubling the food in the basket does not double the time — it wrecks the airflow, which is a different failure. When in doubt, cook less at once and accept the second round; the results are not comparable.

Trust the thermometer, not the converted number

Domestic air fryers vary enormously in real delivered heat — fan speed, chamber size and how accurately the thermostat tracks the dial all differ by model, and none of that is on the box. That is not a reason to distrust the conversion; it is a reason to treat its output as a first estimate and to check early. Two minutes is the difference between golden and burnt at these air speeds, and the first check at 60 percent of the time is where you catch it.

For anything with a safety threshold, colour is not evidence. Poultry that looks perfectly browned can still be short of 165 °F at the joint, and a pork chop can hit 145 °F while its crust is barely coloured — the USDA publishes these minimums precisely because appearance is unreliable. Probe the thickest part, away from bone, and let whole cuts of beef, pork, lamb and veal rest 3 minutes before serving.

Air fryer time

Five conventional-oven recipes converted, with the first check time
Recipe	Oven setting	Air fryer temperature	Air fryer time	First check
Frozen fries	400 °F, 25 min	375 °F	20 min	12 min
Chicken wings	425 °F, 40 min	400 °F	34 min	20 min
Roasted vegetables	425 °F, 30 min	400 °F	25 min	15 min
Salmon fillet	400 °F, 15 min	375 °F	13 min	8 min
Blueberry muffins	350 °F, 20 min	325 °F	18 min	11 min

Air Fryer ConverterConvert any oven recipe to air fryer temperature and time, adjusted for food type and basket load.Try the tool →

Frequently asked questions

Do I actually need to preheat an air fryer?: About three minutes is enough, and it matters most for things that should sear on contact — a steak, a chop, anything breaded. For frozen food and slow-roasting vegetables you can skip it and simply add a couple of minutes, since the food spends the warm-up climbing anyway. The one case where preheating is worth insisting on is baked goods, where a cold start changes how the batter rises.
My recipe is already written for a fan oven. Do I still drop 25 °F?: No — halve it. A fan oven has already made part of the correction, so drop 15 °F instead of 25 °F and take roughly 12 percent off the time rather than 20 percent. Applying the full conventional adjustment twice is the most common reason converted recipes come out underdone, and it is easy to spot: the food is pale at the time the recipe said it would be finished.
Can I use foil or parchment in the basket?: Yes, with two conditions: never during the preheat, because loose paper will be lifted into the element, and never covering the perforations, because blocking the airflow turns the machine into a small bad oven. Cut the liner smaller than the basket floor and let the food weigh it down. For anything you want crisp underneath, skip the liner entirely — the holes are the point.

Articles you may find interesting

All guides →

ExplainerA Cup Is Not a Cup — and That Is Why Your Cake FailedFour different cups are in legal use, and the Australian tablespoon is a third bigger than everyone else's. But the error that actually ruins a bake is smaller than a border: the same cup of flour weighs 120 g or 160 g depending on how you filled it.ExplainerBaker's Percentage Explained: One Formula, Any Batch SizeFlour is 100 percent and everything else is measured against it. That one convention lets the same recipe scale from a single loaf to a bakery batch without a single new calculation — and yes, the percentages are supposed to add up to more than 100.How-toHow to Brine Meat: The Two Methods, and Why a "6 % Brine" Is an Ambiguous InstructionA conventional wet brine is 5 to 6 percent salt by weight of the water and you pull the meat out on a timer. An equilibrium brine is 1 to 2 percent by weight of the meat and water together, and it cannot over-salt. Those are different numbers doing different jobs.How-toHow to Substitute a Cake Pan Size Without Ruining the BakeSwap one cake pan for another by matching their area, then adjust batter depth and baking time so the cake rises and bakes evenly in the pan you actually own.ExplainerPizza Dough Hydration Explained: What the Percentage MeansUnderstand what hydration percentage means, how water-to-flour ratio shapes your crust, and which level to choose for pan, Neapolitan, or New York style pizza.How-toHow Much Tile and Grout You Actually NeedFloor area divided by tile area is the answer everyone reaches for, and it is always short. Count the grid instead, add the layout allowance, round to full boxes, keep attic stock — then derive the grout from the joint geometry rather than trusting the bag.

Sources

Spotted a mistake in this article?