Cake Tin & Pan Volume Scaler
Calculate the exact mathematical batter multiplication ratio between round, square, and rectangular baking pans.
Configure Tin Dimensions
1. Recipe Original Tin
2. Your Target Tin
Multiply every ingredient in your original recipe by 1.32.
Standard British Cake Tin Conversion Matrix
Pre-calculated scaling factors converting standard 20cm (8-inch) round cake recipes into common alternatives.
| Target Pan Size | Surface Area | Scaling Multiplier | Bake Time Adjustment |
|---|---|---|---|
| 15cm (6-inch) Round | 177 cm² | 0.56× | Reduce time by 15-20% |
| 18cm (7-inch) Round | 254 cm² | 0.81× | Reduce time by 10% |
| 20cm (8-inch) Round (Baseline) | 314 cm² | 1.00× | Baseline recipe time |
| 23cm (9-inch) Round | 415 cm² | 1.32× | Increase time by 10-15% |
| 20cm (8-inch) Square | 400 cm² | 1.27× | Increase time by 5-10% |
| 23 × 33cm (9 × 13-inch) Tray | 759 cm² | 2.42× | Reduce time by 20% (Thinner depth) |
The Geometric Fallacy of "One Size Up"
A common mistake in home baking is assuming that moving from an 8-inch (20cm) round cake tin to a 9-inch (23cm) round tin requires only a negligible addition of batter. Geometry disproves this intuition. Because the area of a circle scales with the square of its radius ($A = \pi r^2$), a 1-inch expansion increases total surface area by roughly 32%.
If an unmodified 20cm recipe is poured into a 23cm tin, the batter depth drops significantly. This thin batter layer causes moisture to evaporate rapidly before the chemical leavening agents (sodium bicarbonate, monocalcium phosphate) can produce a light crumb, leading to flat, dry cakes.
Conversely, substituting a 20cm round tin with an 8-inch square tin introduces an extra 27% in surface area because square corners add volume not present in a circle. Our geometric scaling engine ensures your batter maintains its intended depth across any pan geometry.