How tin conversion works
What matters is the base area of the tin. Keep the batter the same depth and the cake bakes in roughly the same time. The calculator compares areas: a round tin's area is π × radius², a square is side², and a rectangle is length × width.
Recipe multiplier = area of new tin ÷ area of original tin
For example, an 8-inch round tin is 50.3 sq in and a 9-inch round tin is 63.6 sq in, so multiply the recipe by 1.27 (about 1¼).
Common tin sizes
| Tin | Area | Same as |
|---|---|---|
| 6-inch round (15 cm) | 28 sq in | about ½ of a 9-inch round |
| 8-inch round (20 cm) | 50 sq in | 7-inch square |
| 9-inch round (23 cm) | 64 sq in | 8-inch square |
| 8-inch square (20 cm) | 64 sq in | 9-inch round |
| 9-inch square (23 cm) | 81 sq in | 10-inch round (79) |
| 9 × 13-inch rectangle | 117 sq in | two 9-inch rounds (127) |
| 9 × 5-inch loaf | 45 sq in | 8-inch round (50) |
Frequently asked questions
Can I bake an 8-inch recipe in a 9-inch tin without changing it?
Yes, but the cake will be about 21% thinner and will bake faster. Start checking 5–10 minutes early. For the same height, multiply the recipe by about 1.25.
How do I scale the ingredients?
Multiply every ingredient by the multiplier shown. The Recipe Scaler does this for a whole ingredient list: set the servings to 1 and the new servings to the multiplier.