Have a recipe for a 20 cm tin but want to bake in a 26 cm tin? This calculator works out the scaling factor for all ingredients in seconds. Enter the old diameter, the new diameter and the number of layers. Works for round tins regardless of measurement unit — grams, millilitres or whole eggs.
Area of a circle = π × r². When the diameter changes, the area ratio = (d_new / d_old)². Example: 26/20 = 1.3, squared = 1.69. The number of layers stays the same — only ingredient quantities change proportionally to the area ratio.
Recipe for a 20 cm tin, baking in a 26 cm tin. Scaling factor = (26 ÷ 20)² = 1.69. If the recipe calls for 200 g flour, 100 g butter and 3 eggs: flour 200 × 1.69 = 338 g, butter 169 g, eggs ≈ 5. Multiply every ingredient by 1.69.
Calculate the scaling factor: (new diameter ÷ old diameter)². Then multiply every ingredient quantity by that factor.
Because the area of a circle grows as the square of the radius (A = π × r²). Using a linear ratio alone would make the cake too thin.
Yes. A larger tin usually means a shallower cake, which can reduce baking time. Check 10 minutes earlier than the recipe states.
Popular sizes: 16 cm (≈6 slices), 18 cm (≈8), 20 cm (≈10–12), 22 cm (≈12–14), 24 cm (≈14–16), 26 cm (≈16–20).
Multiply the egg count by the scaling factor and round to the nearest whole number. If 3 eggs × 1.69 ≈ 5, use 5 eggs.
Temperature usually stays the same. If the cake is much taller (smaller tin, same batter), reduce temperature by 10 °C and extend baking time.
Use surface areas: factor = (new length × new width) ÷ (old length × old width). Example: 25×35 ÷ 20×30 = 875 ÷ 600 ≈ 1.46.
For a standard 8–10 cm tall cake, allow roughly 5 cm per birthday slice. Circumference ÷ 5 gives an approximate portion count.
Calculate top area (π × r²) plus side area (π × d × h). For a 24 cm cake 10 cm tall that is roughly 1206 cm² — plan about 600–800 g of fondant.
For loaf tins, compare the cross-section areas (length × width). For cupcakes, divide the total batter volume by the volume of one cupcake mould.
The result is indicative. Baking time and temperature may need adjustment for a significantly different tin size.
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