Oven Temperatures Explained: Fahrenheit, Celsius, Gas Mark & Fan

Open three recipes and you might see an oven set to "350°F," "180°C," and "gas mark 4." They are the same temperature. A fourth recipe says "160°C fan," which is also, roughly, the same heat. No wonder oven settings cause confusion: four systems are in common use, and most recipes speak only one of them.

This guide covers what each one means, what the common baking temperatures are actually for, and the part almost no recipe mentions: the number on your oven dial and the real temperature inside are often not the same.

Four ways to say the same heat

Fahrenheit (°F): the US standard. Most online recipes default to it.
Celsius (°C): the rest of the world, and the metric standard.
Gas mark: the British scale for gas ovens, numbered ¼ to 9. Each step up is 25°F hotter, starting from gas mark 1 at 275°F.
Fan (convection): not a temperature scale at all, but a separate setting. A fan circulates the hot air, so the oven cooks faster at the same dial number. UK recipes often print both, like "200°C (180°C fan)."

To convert a specific number, the oven temperature converter does all four at once. The rest of this guide is about using them well.

What each baking temperature is for

The number is not arbitrary. Each range does a particular job:

275–325°F (140–160°C, gas ¼–3): low and slow. Drying meringues, slow-roasting meat, custards that must not curdle, keeping food warm.
350°F (180°C, gas 4): the default. Most cakes, cookies, brownies and quick breads are designed around this moderate heat, which cooks the middle before the outside burns.
375–400°F (190–200°C, gas 5–6): a little faster. Muffins, scones, pies, and cookies you want crisp at the edge. Roasting vegetables starts here.
425–450°F (220–230°C, gas 7–8): hot. Bread, pizza, pastry that needs a fast rise and a browned crust, and roasting that should caramelise rather than steam.
475°F and up (240°C+, gas 9): very hot. Artisan bread, high-heat pizza, anything where a short, fierce blast is the point.

Push a recipe much outside its range and the result changes: a cake baked too hot sets a domed, cracked top before the centre is done; bread baked too cool stays pale and dense.

Fan ovens run hotter than the dial says

A fan (or convection) oven moves the air, so heat reaches the food faster and more evenly. The standard adjustment is to drop the temperature by about 20°C (25–30°F) from what a conventional recipe gives, or keep the temperature and shorten the time. So a cake at 180°C conventional goes in at about 160°C fan.

Fan is excellent for roasting and for baking several trays at once, where the even air is a real advantage. For a single cake or a delicate custard, conventional heat is often gentler. If your oven is fan-only and a recipe gives conventional numbers, make the 20°C cut yourself.

Where gas mark comes from

The gas mark scale looks strange until you see the pattern: each mark is 25°F apart, and gas mark 1 is 275°F. So gas mark 4 is 275 + (3 × 25) = 350°F, gas mark 6 is 400°F, and gas mark 7 is 425°F. Below gas mark 1 the scale halves into ½ (250°F) and ¼ (225°F) for the lowest settings. If you remember only one thing, make it that gas mark 4 is 350°F is 180°C, the moderate-oven default most baking starts from.

The part recipes leave out: your oven probably lies

Here is what makes the conversions above only half the story. Most home ovens are off, sometimes by 25°F or more, and they drift as they age. The dial is a target, not a measurement. A recipe can be perfect and still fail because the oven ran 30 degrees hot.

Two cheap habits fix most of it:

Use an oven thermometer. A small hang-in thermometer costs little and tells you the real temperature. Set the oven to 350°F, let it fully preheat, and see what the thermometer actually reads. If it says 325 or 375, now you know to adjust.
Preheat fully, and longer than the beep. Most ovens signal "ready" when the air reaches temperature, but the walls and racks are still catching up. Another 10–15 minutes gives you steady, even heat, which matters most for bread and anything that bakes for only a short time.

Hot spots are the other culprit: most ovens run hotter at the back and on one side. If your cookies always brown unevenly, rotate the tray halfway through. None of this is in the recipe, and all of it changes the result more than a five-degree conversion ever will.

Quick reference

Gas mark 4 = 350°F = 180°C = 160°C fan (the baking default)
Gas mark 6 = 400°F = 200°C = 180°C fan
Gas mark 7 = 425°F = 220°C = 200°C fan
Fan ovens: drop about 20°C / 25°F from the conventional number

For any other value, the oven temperature converter handles °F, °C, gas mark and fan together, and the full temperatures page covers meat doneness, candy stages and slow-cooker heat.