Cake Box Size Guide & Calculator

The single most common question we get is some version of: I have baked an 8 inch cake, what box do I need? This page answers it three ways — a calculator, a chart, and the reasoning behind both.

Cake box size calculator

Cake box size chart

If you would rather just read it off a table, here is the same logic. Sizes assume the cake sits on a board 1 to 2 inches wider than the cake itself, which is how most decorators work.

Cake size	On a board	Box you need	Height it allows
4 inch round	5–6 inch	8.5 x 8.5 x 3 inch	Up to 2.75 inch
5 inch round	6–7 inch	8.5 x 8.5 x 3 inch	Up to 2.75 inch
6 inch round	7–8 inch	8.5 x 8.5 x 3 inch	Up to 2.75 inch
7 inch round	8–9 inch	10 x 10 x 4 inch	Up to 3.75 inch
8 inch round	9–10 inch	10 x 10 x 4 inch	Up to 3.75 inch
9 inch round	10–11 inch	12 x 12 x 5 inch	Up to 4.75 inch
10 inch round	11–12 inch	12 x 12 x 5 inch	Up to 4.75 inch
11–12 inch round	12–14 inch	Custom, ask us	—

The three measurements that actually matter

1. The board, not the cake

This is where most people go wrong. You do not size a box to your cake — you size it to your cake board. An 8 inch cake on a 10 inch drum needs a box that fits 10 inches, not 8. Measure the board.

2. Half an inch of wiggle room

You want the board to slide in without forcing, but not to slide around. Roughly half an inch of total clearance across the width is right. Much more and the cake shifts in transit; much less and you scrape buttercream against the wall getting it in.

3. Height, including the decoration

Measure to the top of the tallest thing on the cake — the drip, the topper, the tallest flower — then add a quarter inch so nothing touches the lid. A standard two-layer 8 inch cake is usually around 4 to 4.5 inches tall with the board, which is why the 10 x 10 x 4 inch box is the most-bought size in the country and also the one people most often find slightly too short. If you decorate tall, go up to the 12 x 12 x 5.

What about square cakes?

A square cake uses more of the box footprint than a round one of the same nominal size, and the corners are what catch. Give a square cake the same box you would give a round cake one inch larger. The calculator above already does this for you.

Tiered cakes

For a stacked tiered cake, size the box to the bottom tier board and to the full assembled height. Most decorators transport tiers separately and assemble on site precisely because a box tall enough for an assembled three-tier cake is unwieldy and expensive. If you must transport assembled, that is a custom box conversation — talk to us.

Cupcakes and cookies are sized differently

Cupcakes go in a box with a fitted insert — 6 x 6 x 3 inch for four, 9 x 6 x 3 inch for six. The insert, not the box, is what keeps buttercream intact.

Cookies want a shallow box, not a deep one. Our 8.5 x 5.25 x 1.5 inch cookie box is deliberately low so a single layer sits snugly and decorated royal-icing work does not slide and chip.

Still not sure?

Send us your cake dimensions and we will tell you which box. If it helps, we will post you free samples of the sizes you are choosing between so you can try before you commit. Ask for samples.