Guide to Cake Sizes

It’s every baker’s worst nightmare: running out of cake! With our handy guide to cake sizes, you needn’t worry. Whether you’re baking a two-layer round cake for a gathering of eight or a six-tiered wedding cake for a crowd of 150, we’ll show you exactly how big you’ll want your cake to make sure you have enough to feed your party and not have too many leftovers.

Cake portion sizes

How big is a slice of cake? It really depends on who’s cutting it! There will inevitably be variations in portion sizes (especially if a cake lover is left in charge of serving up!) but our guides are based on a 2x1 inch slice of cake. On a round cake the 2 inch serving would be measured from the circumference of the cake, whereas a rectangular cake would be measured in 2x1 inch squares.

How to slice a cake

Whether your cake is round, square, rectangle, tiered or in a fun shape – there are certain ways you can cut it to make sure serving sizes are equal and you get the most of the cake. For a round cake, this almost always involves cutting outwards from the centre into slices, whereas square and rectangular cakes can be cut into smaller, equal portions. For themed cakes with an irregular shape, it's often best to cut rectangles or squares from the centre of the cake.

Round cakes

A round cake is a classic – from an all-time favourite jam sponge to a rich and decadent chocolate cake. For small family gatherings and celebrations or to accompany a bigger spread of sweet treats, a 5 inch single layer round cake is perfect. For big events and birthdays, you can get up to 64 servings out of just one layer!

Round cakes should be cut from the centre outwards, with a 2 inch gap between each slice. The portion guide below is based on a single layer, but you can layer up to get more servings from a cake. For instance, making a double layer cake means thinner slices but just as much delicious cake for everyone to enjoy!

Chart of number of portions per size for a single layer round cake from 5 inch (8 servings) to 14 inch (64 servings)

Rectangular cakes

If you’re baking for a big birthday bash or a kids’ party – a rectangular sheet bake is ideal! Perfect for feeding a crowd of cake lovers, rectangular cakes are easy to portion out and serve in mini rectangular bites. If you’re looking for a more substantial slice for an afternoon treat, we recommend halving the serving sizes and dishing up a bigger portion.

Chart of number of portions per size for a single layer rectangular cake from 7x11 inch (24 servings) to 12x18 inch (72 servings)

Square cakes

Like rectangular cakes, square cakes are great if you’re baking for a big crowd. Cut into rectangular pieces, you can get eight slices out of a 5 inch bake.

Chart of number of portions per size for a single layer square cake from 5 inch (8 servings) to 14 inch (98 servings)

Tiered cakes

The more tiers, the more yummy cake there is to go around! This makes it an obvious choice for wedding cakes, as well as big events where there are lots of people to feed. When it comes to tiered cakes, there are two portion sizes – finger portions and dessert portions. Finger portions are 1x1 inch and are ideal if you’re having cake as a party extra, perhaps in the evening after a three-course wedding breakfast. Dessert portions are slightly bigger at 1x2 inches and are substantial enough to be served in place of a dessert.

Chart of number of portions per size for a round tiered cake from 4 inch (10 finger portions, 6 dessert portions) to 12 inch (80 finger portions, 58 dessert portions)

Chart of number of portions per size for a square tiered cake from 4 inch (15 finger portions, 8 dessert portions) to 12 inch (110 finger portions, 70 dessert portions)

Bundt cakes

Similar to round cakes, the bundt cake is great for more intimate occasions like afternoon tea with friends or a small family gathering. A bundt cake tin can vary in size and tends to be deeper than a simple round cake, but it has a hole in the middle, so we recommend using the approximate servings guide for a round cake for bundt bakes.

Loaf cakes

From lemon drizzle to banana bread, loaf cakes are perfect for a smaller gathering with friends or family. Loaf tins come in many sizes and are mainly used for bread, but the most popular choice for cakes is a 3x8 inch tin, which you can expect to get around 10 slices from.