# Oven temperature and pan size converter

> Convert oven temperatures between °C, °F, fan oven and gas mark, and work out how much to scale a recipe for a different round, square or rectangular pan.

Interactive version: https://www.calcopenly.com/everyday/oven-temperature-and-pan-size-converter
Subject: Everyday calculators

Oven temperatures convert with °F = °C × 9/5 + 32. A fan oven is set about 20 °C below a conventional one, and gas mark 1 is 275 °F (140 °C), with each mark adding 25 °F. For pans, the ingredient factor is the area of your pan divided by the area of the recipe's pan, which keeps the batter at the same depth.

The default converts 350 °F: 176.7 °C, which recipes round to 180 °C, or 156.7 °C in a fan oven (usually written 160 °C), and gas mark 4. In pan mode, a 9-inch round pan (63.6 sq in) and an 8-inch square pan (64 sq in) hold almost the same amount, a factor of 1.006.

Oven thermostats and fans vary, so treat the converted setting as a starting point. When batter ends up deeper or shallower than the recipe intended, check for doneness early.

## Inputs

- **Convert** (options: Oven temperature, Pan size)
- **Oven setting**
- **Setting is in** (options: °C, °F, Fan °C, Gas mark)
- **Convert to** (options: °C, °F, Fan °C, Gas mark)
- **Recipe pan shape** (options: Round, Square, Rectangle)
- **Recipe pan diameter**
- **Recipe pan side**
- **Recipe pan length**
- **Recipe pan width**
- **Your pan shape** (options: Round, Square, Rectangle)
- **Your pan diameter**
- **Your pan side**
- **Your pan length**
- **Your pan width**

## Results

- Conventional oven (°C) — main result
- Conventional oven (°F)
- Fan oven (°C)
- Gas mark
- Multiply ingredients by
- Recipe pan area (cm²)
- Your pan area (cm²)
- Recipe pan area (in²)
- Your pan area (in²)

## Formula

$$
\begin{gathered}{}^\circ F = {}^\circ C \times \tfrac{9}{5} + 32 \\ \text{fan} = {}^\circ C - 20 \\ \text{pan factor} = \frac{A_{\text{your pan}}}{A_{\text{recipe pan}}}\end{gathered}
$$

## Worked examples

### 350 °F to °C

- Convert: Oven temperature
- Oven setting: 350
- Setting is in: °F
- Convert to: °C
- **Conventional oven: 176.7 °C**
- **Fan oven: 156.7 °C**
- **Gas mark: 4**
- Checked against: Python decimal: (350 − 32) × 5/9; gas mark 4 = 350 °F (gas mark table)

### 180 °C to °F

- Convert: Oven temperature
- Oven setting: 180
- Setting is in: °C
- Convert to: °F
- **Conventional oven: 356 °F**
- **Gas mark: 4**
- Checked against: 180 × 9/5 + 32 = 356; nearest mark is 4 (350 °F)

### Gas mark 1/4

- Convert: Oven temperature
- Oven setting: 1/4
- Setting is in: Gas mark
- Convert to: °C
- **Conventional oven: 107.2 °C**
- **Conventional oven: 225 °F**
- Checked against: Gas mark table: 1/4 = 225 °F; Python decimal (225 − 32) × 5/9

### Fan 160 °C to °F

- Convert: Oven temperature
- Oven setting: 160
- Setting is in: Fan °C
- Convert to: °F
- **Conventional oven: 356 °F**
- **Conventional oven: 180 °C**
- Checked against: Which? rule: fan + 20 = 180 °C conventional; 180 × 9/5 + 32

### 200 °C to gas mark

- Convert: Oven temperature
- Oven setting: 200
- Setting is in: °C
- Convert to: Gas mark
- **Gas mark: 6**
- Checked against: 200 °C = 392 °F; nearest mark 6 = 400 °F (gas mark table lists 200 °C as mark 6)

### Boiling point is below gas mark 1/4

- Convert: Oven temperature
- Oven setting: 100
- Setting is in: °C
- Convert to: °F
- **Conventional oven: 212 °F**
- **Gas mark: Below 1/4**
- Checked against: 100 × 9/5 + 32 = 212 °F, under 225 °F

## Questions

### What is 180 °C in Fahrenheit?

356 °F, from 180 × 9/5 + 32. Recipes round it to 350 °F, which is gas mark 4, and the Which? oven conversion table puts 180 °C, 160 °C fan, 350 °F and gas mark 4 on the same row. Going the other way, 350 °F is exactly 176.7 °C.

### How much lower should a fan oven be?

About 20 °C lower than the conventional temperature, according to Which?, so 180 °C becomes 160 °C fan and 200 °C becomes 180 °C fan. The fan moves hot air over the food, and leaving the setting unchanged can cook the outside too quickly. Oven makers' manuals give the figure for a specific model.

### What temperature is gas mark 4?

180 °C (350 °F), or 160 °C in a fan oven. Gas mark 1 is 140 °C (275 °F) and each mark adds 25 °F, about 14 °C: gas 6 is 200 °C (400 °F) and gas 9 is 240 °C (475 °F), as listed in the Which? table. The Celsius values are rounded to the nearest 10 °C.

### Can I use an 8-inch square pan instead of a 9-inch round one?

Yes. A 9-inch round pan has an area of π × 4.5² = 63.6 square inches and an 8-inch square pan has 64, so the recipe needs no change. A 9 × 13 inch pan has 117 square inches, 1.84 times the 9-inch round, so batter for the rectangle fills nearly two round pans to the same depth.

### How do you adjust a recipe for a different cake tin?

Multiply every ingredient by the new tin's area divided by the old tin's area. For round tins that is the ratio of the diameters squared: moving from a 20 cm to a 23 cm tin is (23 ÷ 20)² = 1.32, so use about a third more of everything. The batter then sits at the same depth, so the baking time stays close to the original.

### How accurate is the oven temperature and pan size converter?

Accuracy depends on your inputs and the method's assumptions. Decimal arithmetic uses 50 significant digits, but estimates, numerical methods and source data can be less precise; the displayed rounding does not remove those limits. It is checked against 9 worked examples whose answers come from independent sources; for example, “350 °F to °C” is checked against Python decimal: (350 − 32) × 5/9; gas mark 4 = 350 °F (gas mark table).

### Where does the method come from?

Gas mark — conversion table (1 = 275 °F, +25 °F per mark); Which? — Oven temperature conversion table (fan ovens 20 °C lower).

## Sources

- [Gas mark — conversion table (1 = 275 °F, +25 °F per mark)](https://en.wikipedia.org/wiki/Gas_mark)
- [Which? — Oven temperature conversion table (fan ovens 20 °C lower)](https://www.which.co.uk/reviews/built-in-ovens/article/oven-temperature-conversion-table-aA5Ol9b157On)