Oven Temperature Chart

Gas marks are not a conversion of anything. They are a fixed scale of oven settings, so the Celsius column below is the published equivalent rather than a calculated one. The oven dial column is the setting printed on US ovens and in US recipes, in 25-degree steps; the exact column is the Celsius figure converted, for anyone who needs to know how far the rounding goes.

A fan circulates hot air instead of letting it stratify, so food receives heat faster at the same air temperature. The convention is to set a fan oven about 20 °C below the conventional figure to get the same result in the same time.

This is a manufacturer convention rather than a physical constant, and 20 °C is a round number chosen for convenience. Some ovens are better matched at 15 °C and some at 25 °C, so treat the first bake in an unfamiliar oven as a calibration run.

The adjustment is also the single most common cause of a recipe failing across borders. A UK recipe saying "180 °C" usually means conventional, so setting a fan oven to 180 °C overshoots by about 20 degrees and produces a cake that is dark outside and raw in the middle.

An air fryer is a small, powerful fan oven, so the fan adjustment applies and then some. The usual starting point for adapting an oven recipe is to lower the temperature by about 20 °C (25 °F) and cut the time by about 20 percent: a 200 °C, 25-minute oven recipe becomes roughly 180 °C for 20 minutes.

Treat that as a first attempt rather than a rule. Air fryers vary more than ovens, and a basket packed full cooks slower than the same food in a single layer. Check a few minutes early, and shake or turn the food halfway through.

The exact conversion of 180 °C is 356 °F, and every American oven dial says 350 °F. That 6-degree gap is smaller than the swing of a domestic oven thermostat, which typically cycles ±10 °C around its set point, so the rounding is harmless.

What is not harmless is the oven itself. Domestic ovens are frequently 10 to 20 degrees out of calibration, and hot spots within a single oven can differ by more again. An oven thermometer costs very little and tells you more than any conversion chart can.