Quick answer
A 2 layer, 8 inch cake needs a 10 inch board and an 11 by 11 by 6 inch box. A 3 layer version of the same cake needs the same 10 inch board but an 8 inch tall box instead of 6, because only height changes with layer count. Board and box footprint depend only on diameter.
Wilton 10 Inch White Cake Boards, 10 Count
A 10 inch board is the right size under an 8 inch cake, leaving an inch of margin all round to lift by, and this is the branded version of a category dominated by unbranded packs.
Best for: boards under 8 inch cakes
Check price on AmazonA cake board is sized 2 inches over the cake so there is an inch of margin all the way around to lift it by, and a box is sized 1 inch over the board on each side plus 2 inches of headroom above the cake. An 8 inch cake needs a 10 inch board and an 11 by 11 inch box; the box height depends on how tall the cake stands, which depends on how many layers it has, not on how wide it is.
That last point is worth stating plainly, because it surprises people: a 2 layer cake comes out to roughly 3.71 inches tall regardless of its diameter, since height is a function of batter depth and layer count, not floor area. A 3 layer cake of any diameter runs about 5.69 inches. Only the diameter changes the board and box footprint; only the layer count changes the box height. Work out any size in the cake board and box calculator, and see what each tier needs to carry on the tiered cake dowel chart.
The same logic extends past the cake itself to the box lid. A box cut too tight will drag across the top of the cake as the lid closes, catching a piped border or a smooth finish with it, which is why the extra 2 inches of headroom above the cake exists even though it can look generous on paper. Board and box sizes matter most when they have to be ordered or bought ahead of time rather than improvised at the last minute, since bakery supply boxes are typically sold in fixed increments rather than made to measure.
What board and box does a 2 layer cake need?
These assume a standard 2 layer cake at roughly 3.71 inches tall, finished with a normal buttercream coat rather than a thick fondant shell, which can add another quarter inch or so to the overall width and is usually inside the margin already built into the numbers below.
| Cake diameter (in) | Board size (in) | Box size (in) | Box height (in) |
|---|---|---|---|
| 6 | 8 | 9 x 9 | 6 |
| 8 | 10 | 11 x 11 | 6 |
| 9 | 11 | 12 x 12 | 6 |
| 10 | 12 | 13 x 13 | 6 |
| 12 | 14 | 15 x 15 | 6 |
| 14 | 16 | 17 x 17 | 6 |
| 16 | 18 | 19 x 19 | 6 |
What changes for a 3 layer cake?
Only the box height, because a third layer adds height without changing the footprint the board or box has to clear.
| Cake diameter (in) | Board size (in) | Box size (in) | Box height (in) |
|---|---|---|---|
| 6 | 8 | 9 x 9 | 8 |
| 8 | 10 | 11 x 11 | 8 |
| 9 | 11 | 12 x 12 | 8 |
| 10 | 12 | 13 x 13 | 8 |
| 12 | 14 | 15 x 15 | 8 |
| 14 | 16 | 17 x 17 | 8 |
| 16 | 18 | 19 x 19 | 8 |
Does the formula work for square, hexagon or rectangular tiers the same way?
Yes, and this is the useful part: the board and box formula only cares about the cake's widest measurement, not its shape, so a 9 inch hexagon needs exactly the same board and box as a 9 inch round. A decorator who already has a stock of round boards and square boxes in common sizes can reuse them for a hexagon or heart cake of the same width without buying shape-specific packaging.
| Cake, widest measurement (in) | Board size (in) | Box size (in) | Box height, 2 layer (in) |
|---|---|---|---|
| 6 (square) | 8 | 9 x 9 | 6 |
| 8 (square) | 10 | 11 x 11 | 6 |
| 9 (square) | 11 | 12 x 12 | 6 |
| 10 (square) | 12 | 13 x 13 | 6 |
| 12 (square) | 14 | 15 x 15 | 6 |
| 13 (9x13 rectangle, longest side) | 15 | 16 x 16 | 6 |
| 15 (11x15 rectangle, longest side) | 17 | 18 x 18 | 6 |
| 18 (12x18 rectangle, longest side) | 20 | 21 x 21 | 6 |
Should I size the board and box for the finished cake or the raw batter?
Always the finished, frosted cake, never the pan size or the raw batter volume. A cake baked in a 9 inch pan can finish anywhere from 9 to 9.5 inches across once a layer of frosting is added to the sides, and that extra half inch is exactly the kind of gap that makes a board look slightly undersized in photos even though the math above was followed correctly. Measure the actual frosted cake before cutting or ordering a board when precision matters, such as for a client order.
Before this stack leaves the kitchen
A cake box only protects the cake in transit if it is sized to actually clear the decoration, not just the cake itself; sugar flowers, a tall topper or a heavily piped top all need more headroom than the standard 2 inches used above. If the cake is being delivered rather than picked up, ask about allergies before finalizing the order rather than after, and if cakes are being sold rather than given away, check your state cottage food law, since box and labeling requirements for sold baked goods vary widely by state.
What this job actually needs
Wilton 10 Inch White Cake Boards, 10 Count
$14.99A 10 inch board is the right size under an 8 inch cake, leaving an inch of margin all round to lift by, and this is the branded version of a category dominated by unbranded packs.
Best for: boards under 8 inch cakes
Check price on AmazonAmazon prices move often, so check before you buy.
Southern Champion White One-Piece Bakery Boxes, 10 x 10 x 6 in, 100 Count
$91.93A 6 inch tall box clears a tall two layer cake on a board, which the commoner 5 inch boxes do not, and a case of 100 is the unit anyone selling cakes buys in.
Best for: selling or gifting cakes at volume
Check price on AmazonAmazon prices move often, so check before you buy.
Nordic Ware Cake Lifter, 10 in
$25.99A flat 10 inch disc slides under a finished tier without flexing, which is the difference between moving a cake and dropping it.
Best for: moving a finished tier onto its board
Check price on AmazonAmazon prices move often, so check before you buy.
Questions people ask
- Why is a cake board 2 inches wider than the cake instead of an exact fit?
- The extra 2 inches, an inch of margin on every side, gives something to hold onto when lifting or carrying the cake without touching the frosted surface. An exact-fit board leaves no edge to grip, and any pressure on the cake itself risks denting the finish. It is a trade convention rather than a fixed rule, and some decorators add more margin for a heavier or taller cake.
- Why does the box need to be bigger than the board, not just the same size?
- A box sized exactly to the board would scrape frosting off the cake every time it went in or came out, since a cake on its board takes up real space and boxes are rigid. An extra inch of clearance on each side lets the board slide in without contact, and rounding the box dimensions up to a whole inch matters because commercial bakery boxes only come in whole-inch sizes.
- How much headroom does the box need above the cake itself?
- Two inches above the top of the finished cake, which covers a normal buttercream finish plus a low piped border without touching the lid. A cake with a tall topper, sugar flowers standing above the surface, or a very heavily piped top needs more than the standard 2 inches, and that has to be judged case by case rather than read off this chart.
- Does frosting thickness change the board or box size?
- Not meaningfully. A crumb coat and final coat add a fraction of an inch to the cake's overall width and height, well inside the margin already built into the board and box formula. What does change the numbers is the cake's actual diameter and its height from the layer count, both of which are accounted for directly in the tables above.
- My cake diameter is not on this chart. How do I size the board and box myself?
- Add 2 inches to the cake's diameter for the board, add another inch on each side beyond that for the box footprint, and add 2 inches to the cake's finished height for the box height, rounding everything up to a whole inch since boxes and boards both come in whole-inch sizes. The cake board and box calculator does this arithmetic for any size, including odd or shape-specific diameters not shown here.
Related pages
How this page was put together
Researched from pan geometry, published manufacturer capacities, published serving conventions and university extension guidance. Not hands-on testing, and not professional advice.
Figures are labelled as derived, published or trade convention. Where no honest figure exists, the page says so rather than filling the gap.