Work out cake size for guests instantly with clear inputs, formula shown and shareable results.
Cake servings come from area, not diameter. A dessert portion is about 2 square inches of surface, so 60 guests need 120 square inches spread across the tiers. A square cake yields roughly 27% more servings than a round one of the same width.
Cake sizing
area needed = guests x area per serving; round diameter = 2 x sqrt(area / pi)
Its area is the side squared while a round cake of the same width is pi/4 of that — about 78%. Square also cuts into neat rectangles with no waste.
The top tier is often kept, so plan servings from the lower tiers and treat the top as decorative.