400°F to Celsius — all four oven scales
The exact conversion is (°F − 32) × 5/9, so 400°F works out to 204.4°C. Recipe writers round this to 200°C — the long-standing pairing that also maps to gas mark 6 — because no home oven holds a fraction of a degree and no dial displays one. The 4.4°C of rounding is far smaller than a typical oven's swing around its set point.
In a fan (convection) oven, use 180°C — the standard adjustment is conventional minus 20°C, because moving air transfers heat faster than still air. Make the temperature adjustment or shorten the bake time by about a quarter, never both. Bake times are otherwise unaffected by converting between scales: 200°C and 400°F are the same heat wearing different units.
Where 400°F sits on the chart
| °F | °C | Fan °C | Gas mark | Descriptor |
|---|---|---|---|---|
| 350°F | 180°C | 160°C | 4 | Moderate |
| 375°F | 190°C | 170°C | 5 | Moderately hot |
| 400°F | 200°C | 180°C | 6 | Moderately hot |
| 425°F | 220°C | 200°C | 7 | Hot |
| 450°F | 230°C | 210°C | 8 | Hot |
See the full chart on the oven temperature converter →
What bakes at this temperature
400°F / 200°C is the territory of crusty breads, choux pastry and biscuits. Remember that most home ovens swing ±25°F around their set point and many run permanently hot or cold — a standalone oven thermometer on the middle rack tells you more than any conversion chart can.