Scale a round cake to a different tin, see how large each slice is, and put a selling price on it.
| Scale factor | – |
| New batter | – |
| Slice | – |
| Sell price | – |
Use this calculator when the batter is written for a 20 cm tin and you only have a 24 cm one, or when you need a cost-plus price for a birthday cake.
The scale factor is (new diameter ÷ old diameter)² because area grows with the square of the diameter. Depth is assumed the same. New batter is old batter × that factor. Slice area is the new tin’s area divided by how many guests. Price is cost × (1 + margin percent ÷ 100), a home-bakery markup, not a full P&L. For rectangular tins, use equivalent diameters or scale by length × width yourself. Diameters can be centimetres or inches; batter mass can be grams, ounces, or pounds.
Old pan diameter: Diameter of the tin the recipe was written for. 20 cm is a common round cake tin.
New pan diameter: Diameter of the tin you will actually bake in. 24 cm is a step up.
Old batter: Batter mass the original recipe makes. 500 g is a modest sponge.
Slices / guests: How many slices or guests you will cut for. 12 is a typical party cake.
Cost: What the ingredients cost you, in your currency.
Margin (%): Markup as a percent. Type 50 to sell at 1.5× cost.
Scale factor: Area ratio of the two tins.
New batter: Scaled batter mass.
Slice: Area of one slice of the new cake.
Sell price: Cost plus the chosen margin.
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