What this calculator does
Cake pan size converter works out rescales a recipe's batter amount when swapping to a different pan shape or size. Enter your own figures above and the answer updates as you type: nothing is fixed in the code, so the result reflects exactly the numbers you supply.
The formula this calculator evaluates is printed under the tool and explained below, so you can check the working by hand or reuse it in a spreadsheet.
The formula
FormulaRound area = π×(diameter/2)²; rectangular area = length × width; scaled batter = original batter × new area / old area
The inputs explained
| Field | What to enter |
|---|---|
| Original pan shape | Choose from Round, Rectangular. |
| Original diameter (round) (cm) | A number, measured in cm. Starts at 23. |
| Original length (rect) (cm) | A number, measured in cm. Starts at 33. |
| Original width (rect) (cm) | A number, measured in cm. Starts at 23. |
| New pan shape | Choose from Round, Rectangular. |
| New diameter (round) (cm) | A number, measured in cm. Starts at 20. |
| New length (rect) (cm) | A number, measured in cm. Starts at 23. |
| New width (rect) (cm) | A number, measured in cm. Starts at 23. |
| Original recipe batter volume (L) | A number, measured in L. Starts at 1.5. |
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How the answer changes with original diameter (round)
Every other input is held at the calculator’s starting values while original diameter (round) varies. Select any row to load that scenario into the calculator.