Oven temperatures · gas mark guide
Gas Mark 1 in °C, fan and °F
Gas Mark 1 is 140°C in a conventional electric oven, 120°C in a fan oven and 275°F. It is a very low oven, the usual setting for slow-cooked stews and rich fruit cakes such as Christmas cake.
Chart checked against Delia Smith and Waitrose on .
Conventional oven
140°C
electric, no fan
Fan oven
120°C
20°C lower
Fahrenheit
275°F
exactly 135°C
Heat
Very low
gas mark 1
Gas Mark 1 and the settings either side
Conventional and fan temperatures in °C, with °F for American recipes.
| Gas mark | Conventional | Fan | Fahrenheit | Heat |
|---|---|---|---|---|
| Gas ¼ | 110°C | 90°C | 225°F | Very cool |
| Gas ½ | 120°C | 100°C | 250°F | Very cool |
| Gas 1 | 140°C | 120°C | 275°F | Very low |
| Gas 2 | 150°C | 130°C | 300°F | Very low |
| Gas 3 | 170°C | 150°C | 325°F | Low |
Fan ovens
If your electric oven has a fan you cannot switch off, set it to 120°C instead of 140°C. Delia Smith's advice is to take 20°C off conventional temperatures, or check your oven's handbook, as some models run hotter than others.
Why the numbers are rounded
275°F is exactly 135°C. Recipe charts round it to 140°C because ovens are not accurate to a few degrees anyway. An oven thermometer is the best way to know what your oven is really doing.
Related conversions
- Gas mark ½ (120°C · 250°F)
- Gas mark 2 (150°C · 300°F)
- 140°C to gas mark (conventional and fan)
- 275°F to gas mark (US recipes)
Common questions
What is Gas Mark 1 in Celsius?
140°C in a conventional oven, or 120°C if your oven has a fan.
What is Gas Mark 1 in a fan oven?
120°C. Fan ovens cook faster because the fan moves hot air around the food, so set them about 20°C lower than a conventional oven.
What is Gas Mark 1 in Fahrenheit?
275°F. That is the figure American recipes use for a very low oven.
What do you cook at Gas Mark 1?
Slow-cooked stews and rich fruit cakes such as Christmas cake.
Sources and assumptions
- Conventional means an electric oven with the fan off. Fan settings are 20°C lower.
- Recipe charts round temperatures to the nearest 10°C or 25°F, so exact conversions differ by a few degrees.
- Delia Smith: oven temperatures and conversions (gas marks 1 to 9, fan ovens)
- Waitrose: conversion charts (gas marks ¼ and ½)
Ovens vary. An oven thermometer shows what yours is really doing.