What size cake do I need for 15 guests?

With party-style slices, a single 16 cm round cake is the calculator's minimum estimate. Add buffer for larger slices or leftovers.

Can I convert a round pan to a square pan?

Yes. Enter the original and target pan shapes and sizes, then multiply ingredients by the scaling factor.

Does this estimate cake weight?

No. It estimates area and serving size. Cake weight depends on recipe, filling, frosting and height.

Cake Size Calculator

Estimate cake size by guest count, serving style and tiers, or convert a recipe between round, square and rectangular cake pans.

Number of guests

Number of tiers

Serving size

Recommended cake

16 cm

Typical cake height

4-5 in

16 cm

Slice basis: 12.5 cm² per guest (1 x 2 in). Base area needed: 188 cm².

The minimum is rounded to the nearest common round pan diameter. For weddings and birthdays, add 10-15% practical buffer when guests may take seconds or leftovers.

Estimate cake size by guests

Cake-size intent combines two tasks: choosing a cake for guests and converting a recipe to another pan size. This calculator handles both with area-based estimates.

Serving style	Approximate cut	Area model	Use case
Dessert	2 x 2 in	25 cm²	Cake is the main dessert
Party	1 x 2 in	12.5 cm²	Birthday or party table
Wedding	1 x 1 in	6.25 cm²	Small slice after a meal

D = 2 \frac{N \cdot S _{p or t i o n}}{π}

D - round cake diameter, N - guests, Sportion - serving area.

Convert cake pan sizes

For similar cake height, ingredient amounts scale with the base area of the pan. Very different pan depths can still require baking-time adjustments.

k = \frac{A _{n e w}}{A _{o l d}}

k - recipe scaling factor, Anew - new pan area, Aold - original pan area.

When pan area changes by 1.5x or more, check baking time and doneness carefully.

Frequently Asked Questions

Sources and References

Calculations are based on the listed reference sources. Links open in a new tab.

Updated: June 2, 2026

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