Calculator
Baking tin size converter
Swap a round tin for a square one, or a 20 cm for a 23 cm, and scale the batter.
Common tin swaps
Tins with the same area hold the same depth of batter, so they bake in about the same time.
| Recipe’s tin | Swap for | Multiply ingredients by |
|---|---|---|
| 20 cm (8 in) round | 18 cm (7 in) square | about 1 (0.97) |
| 23 cm (9 in) round | 20 cm (8 in) square | about 1 (1.01) |
| 20 cm (8 in) round | 23 cm (9 in) round | 1.27 |
| 20 cm (8 in) square | 23 × 33 cm (9 × 13 in) | 1.83 |
| Two 20 cm (8 in) rounds | 23 × 33 cm (9 × 13 in) | 1.16 |
| 23 × 13 cm (9 × 5 in) loaf | 20 cm (8 in) square | 1.42 |
Adjusting the baking time
- Same depth, different area: the time stays about the same. This is what scaling the ingredients gives you.
- Shallower batter (a bigger tin without scaling up) bakes faster. Start checking 5–10 minutes early.
- Deeper batter takes longer. Lower the oven by 10 °C (25 °F) so the outside doesn’t burn before the middle sets.
- Square tins bake slightly faster at the corners than round ones. Check the middle with a skewer; it should come out clean or with a few moist crumbs.
Measure a tin across the top inside edge, not the outside or the base. For eggs, round the scaled amount to the nearest whole egg, or beat the eggs and weigh them: one large egg is about 50 g out of the shell.