The two formulas that do all the work
Converting oven temperatures comes down to two tidy formulas. To go from Fahrenheit to Celsius, subtract 32 and multiply by 5/9: °C = (°F − 32) × 5/9. To go the other way, multiply by 9/5 and add 32: °F = °C × 9/5 + 32. So a 350°F oven is (350 − 32) × 5/9 ≈ 177°C. These are exact relationships, not estimates — the only rounding happens because ovens are usually set in nice round numbers.
Worth remembering: the two scales meet at −40°, where −40°F and −40°C are the same temperature. Not useful for baking, but a fun sanity check that your math is pointing the right way.
What "Gas Mark" actually means
If you're following an older British or Commonwealth recipe, you'll meet the Gas Mark scale, which is what gas oven dials use there instead of degrees. Gas Mark 1 is about 275°F (135°C), and each whole mark steps up by roughly 25°F (about 14°C). The everyday range runs from Gas Mark ¼ (around 225°F) up to Gas Mark 9 (around 475°F). Because the marks land on fixed reference temperatures rather than a clean formula, the quick reference chart on this page is the most reliable way to read across — that's exactly what it's there for.
The temperatures you'll actually use
Most home baking lives in a fairly narrow band. A few anchors cover the majority of recipes:
- 325–350°F (160–177°C) — cakes, cookies, custards, and most casseroles
- 375–400°F (190–205°C) — muffins, pies, and roasting vegetables
- 425–475°F (220–245°C) — bread, pizza, and anything you want crisp and browned
- 250–300°F (120–150°C) — slow roasting, meringues, and gentle drying
350°F (177°C, Gas Mark 4) is the workhorse setting — if a recipe is vague, it's a safe default for a lot of baked goods.
Convection (fan) ovens run hotter than the dial
A fan oven moves hot air around, so food cooks faster and more evenly than in a conventional oven at the same setting. The common rule of thumb is to drop the temperature by about 25°F (roughly 15–20°C) when a recipe was written for a conventional oven, or to shorten the bake time a little. Manufacturers vary, so treat that as a starting point and watch the food, not just the timer. Many recipes now list both "conventional" and "fan" temperatures to save you the mental math.
Why your oven might be lying to you
Even a good oven can run 25°F or more off its dial, and it swings as the element cycles on and off. If your bakes brown too fast or stay pale, an inexpensive standalone oven thermometer is the fix — it tells you the real temperature inside, so you can adjust the dial to match. It also helps to give the oven a full 10–15 minutes to preheat, since the indicator light often clicks off before the oven walls are truly up to temperature.