How wide is a standard party portion?

A standard party or finger portion is about 2.5cm wide and cut to the full depth of the cake. These are the slim slices typically served at weddings and large celebrations where cake is one of many sweet items.

What size is a dessert portion?

A dessert portion is typically 4cm wide — a generous slice for when cake is the main dessert course. These are roughly twice the volume of a party portion.

How do I cut a round cake for maximum portions?

For maximum portions from a round cake, cut it into concentric rings (for very large cakes 25cm+), then cut each ring into portions. For standard sizes, cut through the centre into wedges.

How accurate are these portion estimates?

The calculation gives a good planning estimate. In practice, you may get slightly fewer portions due to crumbling edges and uneven cuts. For catering, add 5-10% extra to be safe.

What is a standard cake portion size?

For a celebration cake, a standard portion is a slice approximately 2.5cm wide x 5cm deep x the height of the cake. For a generous buffet-style portion, increase to 3-4cm wide. For a wedding cake, portions are often cut smaller (2cm x 5cm) as guests typically have other desserts available.

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Cake Portions Calculator

Calculate how many portions a cake yields based on tin size and slice dimensions.

Cake Shape

Portion Size

Diameter

How We Calculate This

Portion counts depend on the cake's area and how wide you cut each slice. For round cakes, portions are calculated using the formula: area ÷ (slice width × radius). For square and rectangular cakes, the number of slices along each dimension is multiplied.

Formulas

Round: Portions ≈ (π × r²) ÷ (slice width × r)
Square: Portions = (side ÷ slice width)²
Rectangular: Portions = (length ÷ slice width) × (width ÷ slice width)

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Last updated: February 2026

All calculations are based on standard ratios and conversions. Results may vary with specific ingredients, equipment, and conditions.