Donaldson R F Cake Tin Converter
Baking in a different tin from the recipe? Enter both tins in centimetres to get the multiplier for your ingredients and the size of a matching tin.
Guidance only — estimate, not advice. Baking time and cake height change with tin shape, depth, material and your oven. This tool works out geometry and does not give oven times; always check the cake early.
Tin in the recipe
Tin you have
Tins with the same base area as the recipe tin
Tins with the same volume, at your tin's height
How the conversion works
The tool measures how much batter each tin can hold. The base area is π × (diameter ÷ 2)² for a round tin, side × side for a square tin and length × width for a rectangular one. The multiplier by area is the area of your tin divided by the area of the recipe tin: multiply the ingredients by it to get a cake of the same depth. If you enter both heights, the multiplier by volume (base area × height) shows how full the tin would be with the same fraction of batter; without heights, the tool assumes both tins are equally deep, so the two multipliers are the same.
For example, going from a 20 cm round tin to a 20 cm square tin multiplies the recipe by about 1.27, because the square tin has about 27% more base area. A 23 × 13 cm loaf tin is a different shape again, so use the equivalent sizes list above to find a tin that is close. Measure across the inside base of both tins in the same way, so the comparison is fair.
Time and height are not calculated. A larger base gives a shallower cake, which generally needs less time; a smaller or deeper tin generally needs more. Corners and dark metal tins cook faster, and every oven differs. Check the cake early and use a skewer or the recipe's own tests for doneness. For scaling the ingredients themselves see the Recipe Scaler; for oven settings see the Oven Temperature Converter and for measures the Cooking Measurement Converter.
Source / Last verified: plane-geometry area formulas only (circle π r², square, rectangle); no external data. No baking times or tin-size tables are used because no primary source could be confirmed for them. Formulas checked on 26 September 2026 against known values (20 cm round = 314.16 cm²; 18 cm square = 324 cm²).