Cake Servings Calculator
Calculate servings from a round, square, or sheet cake by size and slice dimensions.
For wedding cakes, birthdays, and catering portion planning.
Cake serving size calculations depend on the cake shape, dimensions, and whether it is a dessert slice (smaller, richer cakes) or a party slice (larger, single-layer sheet cakes).
Standard Serving Dimensions:
- Party slice: 1 inch wide × 2 inches deep (finger food at large events)
- Dessert slice: 1.5–2 inches wide × 2 inches deep (seated dinner)
- Wedding cake: 1 inch wide × 2 inches deep (small — typically served with other food)
Round Cake Servings Formula:
Servings = π × r² / (Slice Width × 2)
For a 2-layer cake, multiply by 2 (since both layers count as one serving together).
Worked example — 9-inch round, 2-layer: r = 4.5 inches Area = π × 4.5² = 63.6 sq in At 1.5-inch party slice: 63.6 / (1.5 × 2) = 21 servings
Quick serving reference — standard round cakes (2 layers):
| Diameter | Party (1" slices) | Dessert (1.5" slices) |
|---|---|---|
| 6 inch | 12 | 8 |
| 8 inch | 20 | 14 |
| 9 inch | 24 | 18 |
| 10 inch | 38 | 26 |
| 12 inch | 56 | 40 |
Sheet cake servings (1-layer):
| Size | Party (2"×2") | Dessert (3"×2") |
|---|---|---|
| 9×13 | 24 | 12 |
| 11×15 | 35 | 18 |
| 12×18 | 54 | 27 |
Tiered wedding cakes: Calculate each tier separately, then sum. The top tier is traditionally saved for the first anniversary — subtract that tier from your count.
Planning buffer: Always calculate 10–15% extra servings at events — late arrivals, second helpings, and kitchen waste (end pieces, crumbled slices) consistently reduce actual portions.
How we build and check this calculator
This calculator runs entirely in your browser, so the numbers you enter stay on your device. The math behind it is written by hand and tested against worked examples and standard references before the page goes live.
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