What size cake board do you need?
Board size, board thickness and the box that fits, including the tier that has to sit on top of another cake.
Free. No signup needed.The short answer
An 8 inch cake needs a 10 inch board to carry it, or a 12 inch drum if it is decorated round the base, and an 11 inch box. The board under a stacked tier is the exception: it matches the tier exactly, because it has to disappear under the cake above.
What size cake board do you need?
BakerInbox
The cake
Something to carry the cake on. An inch of board each side to get your fingers under.
Board size
10 in (25 cm)
1 in of board showing each side.
Board to buy
Cake board
3 to 6 mm. Enough under a single sponge.
Into the box
Box size
11 in (28 cm)
The board plus an inch, so it goes in flat and comes out again.
Box depth
6.5 in
Cake and board, plus 2 in for a dome or a topper.
The size follows the job, which is why published charts disagree. A base to carry the cake on gets an inch each side. A presentation drum gets an inch and a half, plus however far your decoration comes out past the base. A board under a stacked tier matches the tier exactly, because it has to sit hidden under the cake above. Box sizes are internal, so a board the same size as the box goes in with nothing to spare.
Board and box sorted. BakerInbox keeps the order, the quote and the delivery date in one place.
Start free trialBoard and box size by cake size
| Cake tin | Base board | Presentation drum | Under a stacked tier | Box |
|---|---|---|---|---|
| 6 in (15 cm) | 8 in | 9 in | 6 in | 9 in |
| 7 in (18 cm) | 9 in | 10 in | 7 in | 10 in |
| 8 in (20 cm) | 10 in | 11 in | 8 in | 11 in |
| 9 in (23 cm) | 11 in | 12 in | 9 in | 12 in |
| 10 in (25 cm) | 12 in | 13 in | 10 in | 13 in |
| 12 in (30 cm) | 14 in | 15 in | 12 in | 16 in |
| 14 in (36 cm) | 16 in | 18 in | 14 in | 18 in |
| 16 in (41 cm) | 18 in | 20 in | 16 in | 20 in |
Boards and boxes are sold in inches, so only the tin column carries centimetres. A base board is the cake plus an inch each side. A presentation drum is the cake plus an inch and a half each side, and more again if decoration sits round the base. A board under a stacked tier is the same size as the tier, because it has to disappear under the cake above. The box column is the base board plus an inch, which is the least that goes in flat and comes out again.
How deep the box has to be
| Finished cake height | Box depth |
|---|---|
| 3 in (8 cm) | 5.5 in |
| 4 in (10 cm) | 6.5 in |
| 5 in (13 cm) | 7.5 in |
| 6 in (15 cm) | 8.5 in |
| 8 in (20 cm) | 10.5 in |
The board sits under the cake, so it counts. These are the cake on a 12 mm drum plus 2 in of headroom for a domed top, a topper, or a hand pressing on the lid. A thinner board saves about a third of an inch, which rarely changes the box you buy. Measure to the tallest thing on the cake, not to the icing.
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Board size, thickness and box
How much bigger depends on what the board is for. A base to carry the cake on is the cake plus 2 inches. A presentation drum is plus 3 to 4. A board under a stacked tier is exactly the tier size.
Why the charts disagree
Two inches or four? Both, for different jobs
Search this and you get one guide saying a board is two inches bigger than the cake and the next saying four to eight. Neither is wrong. They are answering different questions. Two inches is a base: something to carry the cake on and lift it by. Three to four is a presentation drum, where board is meant to show around the cake and take a ribbon. The number that matters is not the cake size, it is what the board is for.
The one every chart gets wrong
A board under a stacked tier is the same size as the tier
A tier that sits on top of another cake gets a board exactly its own size. A 6 in tier goes on a 6 in card. Any bigger and the rim shows all the way round the join, and no amount of icing hides it. The board is still doing real work, spreading the tier's weight across the dowels below, so it does not come out. Only the bottom tier gets a board bigger than the cake. Work out how many dowels each tier needs before you stack.
Thickness
A thin card for the tiers, a 12 mm drum for the base
Thickness follows the same logic. A board under a stacked tier has to be almost invisible, so it is a thin card, 1 to 3 mm. The bottom of a stacked cake carries everything above it and gets picked up by the edge, so it is a 12 mm drum. A single sponge on its own is happy on a plain 3 to 6 mm board. A rich fruit cake is heavy for its size and wants the drum even on one tier.
The box
The box has to clear the board, not the cake
This is where cakes get damaged. Box sizes are internal, so a 10 in board in a 10 in box is an exact fit with nothing spare: you cannot get your fingers down the side, a ribbon on the board edge will not go, and lifting it out drags the icing up the wall. Give the board an inch. Then check the depth, measuring to the tallest thing on the cake rather than to the icing. Once it is boxed it still has to travel, so price the delivery properly.
Buying once
Size the cake first, then the board
Boards are cheap and postage is not, so the waste is ordering twice. Settle the tin before you settle the board: how many portions your tin gives decides the size, and the tin conversion calculator sorts out a recipe written for a different one. Then add the board, the drum and the box to the same order.
FAQ
Common questions
How much bigger should a cake board be than the cake?
Two inches bigger if the board is a base to carry the cake on, so an inch each side. Three to four inches bigger if it is a presentation drum with board showing around the cake, and more again if decoration sits round the base. If the board goes under a tier that stacks on another cake, it is not bigger at all, it is exactly the tier size.
What size board for a 10 inch cake?
A 12 inch board to carry it, or a 13 inch drum if you want board showing around the base. Use a 12 mm drum rather than a thin board, because a 10 inch cake is heavy enough to flex one. If the 10 inch is a tier in a stacked cake, it goes on a 10 inch card instead.
Does a 10 inch cake board fit in a 10 inch cake box?
Only just, and not in practice. Box sizes are internal, so a 10 inch board in a 10 inch box is an exact fit with no clearance: no room for your fingers, none for a ribbon on the board edge, and no way to lift it out without dragging the icing up the side. Suppliers do sell them as a pair, which is why the advice conflicts. Use an 11 inch box, or 12 if the board is ribboned or the cake is delicate.
What size cake board should I use for a 6 inch heart cake?
An 8 inch board, measured across the widest point of the heart, the same plus two inches as any other shape. A heart board in that size looks neatest, and a round or square 8 inch works because a heart sits inside its own square. For a decorated drum, go to 9 inches.
What size box do I need for an 8 inch cake?
An 11 inch box, because the box has to clear the board rather than the cake. An 8 inch cake sits on a 10 inch board, and the board needs an inch of clearance to go in flat and come out again. For depth, a 4 inch tall cake wants about 6.5 inches, measured to the tallest thing on the cake.
Is a 20cm cake tin 8 inches?
20 cm is 7.9 inches, and it is sold and used as an 8 inch tin. The rest of the UK set rounds the same way: 15 cm is 6 inches, 23 cm is 9 inches, 25 cm is 10 inches, and 30 cm is 12 inches. Size the board off the inch figure, since boards and boxes are sold in inches.
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