How big should the cake be? A guide to servings and diameter

The most frequent question when ordering a cake is how many people it will serve. The answer depends not only on the number of guests but also on the size of the slice and when the cake will be served. The guide below rests on practical measures used in patisserie.

What is a standard slice?

For teatime a slice is expected to be about 100 grams, and 130–150 grams when served as a single dessert after dinner. On a round cake the surface area per person is taken as about 26 cm², so a 20 cm cake is enough for 12 and a 26 cm cake for 20 guests.

Diameter table

• 16 cm: 6–8 servings
• 20 cm: 10–12 servings
• 24 cm: 14–16 servings
• 26 cm: 18–20 servings
• 32 cm: up to 30 servings

Square and tray cakes

A 30x40 cm tray cake serves 30–35 people with standard slices and 40 for a light treat. At corporate events a tray cake makes both cutting and serving easier.

When are tiers needed?

A cake above 32 cm diameter is impractical both to transport and to slice. For more than 30 guests we suggest two tiers and for more than 70 three. The size gap between tiers (for example 32, 24, 16 cm) also gives a visually balanced look.

If there are other desserts

If other desserts will also be served after the meal, you can reduce the portion estimate by 20–30%. At children's parties, since an adult slice can be split between two children, count children by half and parents in full.

Use our calculator

The Cake Size Calculator on our site shows the suggested diameter, tiers and estimated price when you enter your guest count and slice size. The result is a starting point; our cake chef finalises it at the design consultation.

One last tip: if the guest count is uncertain, calculate for two extra people rather than one too few. Leftover slices can be frozen, while a cake that falls short overshadows the celebration.

Common mistakes

• A bigger cake does not always mean more people: A tall but narrow cake gives fewer slices than a wide, low one.
• Assuming not everyone will eat cake: At parties with children everyone wants cake; do not lower the count.
• Forgetting the decoration: The weight of fondant and figures reduces the edible portion; with figure cakes the edible weight is 15% lower.

Freezing and storage

You can wrap leftover slices in foil and keep them in the freezer for up to three months. Thaw in the fridge for 8 hours before eating. Do not thaw cream cakes at room temperature.