What this calculator does
Cake servings works out how many servings a round or rectangular cake yields at a given slice 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
Formulaservings = cake area / serving area; round area = πr²; rectangular area = length × width
The inputs explained
| Field | What to enter |
|---|---|
| Shape | Choose from Round, Rectangular. |
| Diameter (if round) (cm) | A number, measured in cm. Starts at 25. |
| Length (if rectangular) (cm) | A number, measured in cm. Starts at 30. |
| Width (if rectangular) (cm) | A number, measured in cm. Starts at 20. |
| Serving size (cm²) | A number, measured in cm². Starts at 13. |
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 diameter (if round)
Every other input is held at the calculator’s starting values while diameter (if round) varies. Select any row to load that scenario into the calculator.