What is the difference between a cake board and a cake drum?

Thickness and purpose. A board is thin card, usually under an eighth of an inch, and sits under individual tiers inside a stack. A drum is around half an inch thick and rigid, and goes under the whole finished cake as the base it is carried and presented on. A drum holds a tiered cake; a board on its own will flex.

Why does the box height matter so much?

Because the lid touching the top of a cake ruins the finish instantly, and it is the dimension people forget to check. The box has to clear the cake, the board it sits on and a little air. A 4 inch cake on a board needs about a 6 inch box, and the commoner 5 inch boxes are sized for something shorter.

Can I use any cardboard as a cake board?

Not for anything that has to last. Ordinary cardboard absorbs fat from the buttercream, goes translucent, and softens to the point where it will not support the cake if you try to lift it. Grease resistant boards are coated to stop exactly that, and it is the one specification worth checking on a product that otherwise looks identical.

Does a square cake need a square board?

It looks better on one, and the same margin rule applies: the board should be about two inches wider than the cake in both directions. A round board under a square cake leaves the corners overhanging with nothing beneath them, which is both awkward to present and genuinely difficult to lift without damage.

Tiered cakes

Cake Board and Box Size Calculator

The board and box a finished cake needs, including the height most people get wrong.

Quick answer

An 8 inch cake wants a 10 inch board and an 11 by 11 by 6 inch box. The board gives an inch of margin all round to lift by, and the box height is the measurement people get wrong: it has to clear the cake plus the board, not just the cake.

Cake width across (in)

Finished cake height (in)

Result

A 10 in board

and a 11 x 11 x 6 in box

Every figure, with what it is based on
Figure	Value	Basis
Board	10 in An inch of margin all round to lift the cake by	Trade convention
Box footprint	11 x 11 in	Trade convention
Box height	6 in This is the measurement people get wrong	Trade convention
Board specification that matters	Grease resistant Plain cardboard goes translucent and soft under a buttercream cake within a day	Trade convention

board = cake width + 2 in, box = board + 1 in, box height = cake height + 2 in

All of these are trade conventions. Boxes come in whole inches, so round up rather than down, and check the interior height rather than the stated size.

The formula

board = cake width + 2 in, box = board + 1 in, box height = cake height + 2 in

All three of these are trade conventions rather than standards, and they exist because of what goes wrong without them. A board only as wide as the cake gives you nothing to hold. A box only as tall as the cake crushes the top the moment the lid closes.

The specification that actually matters on a board is grease resistance, not thickness. Plain cardboard goes translucent and soft under a buttercream cake within a day, and a board that has gone soft cannot be lifted.

Boxes come in whole inches, so round up. Check the interior height rather than the stated size, because some are quoted externally.

Derived, published or convention?

Every figure here is TRADE CONVENTION. There is no published standard for how much margin a cake board should have; these are simply what works and what the trade uses.

Board and box sizes by cake diameter
Cake (in)	Board (in)	Box footprint (in)	Box height for a 4 in cake	Box height for a 6 in cake
4	6	7 x 7	6 in	8 in
6	8	9 x 9	6 in	8 in
8	10	11 x 11	6 in	8 in
9	11	12 x 12	6 in	8 in
10	12	13 x 13	6 in	8 in
12	14	15 x 15	6 in	8 in
14	16	17 x 17	6 in	8 in
16	18	19 x 19	6 in	8 in

Trade conventions throughout. Round up to the nearest whole inch, since that is how boxes are sold.

Gear for these numbers

These are rendered from the verified catalog and re-ordered against your numbers once you calculate.

Beginner

Wilton

Wilton 10 Inch White Cake Boards, 10 Count

$14.99

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 Amazon

Amazon prices move often, so check before you buy.

Expert

SOUTHERN CHAMPION TRAY

Southern Champion White One-Piece Bakery Boxes, 10 x 10 x 6 in, 100 Count

$91.93

A 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 Amazon

Amazon prices move often, so check before you buy.

Beginner

Ohuhu

Ohuhu Cake Carrier with Lid and Handle, fits 10 in Cakes

$23.99

A locking carrier is what gets a decorated cake into a car intact, and a 10 inch interior is the size that actually clears an 8 inch cake on its board.

Best for: transporting a finished cake

Check price on Amazon

Amazon prices move often, so check before you buy.

Questions people ask

What is the difference between a cake board and a cake drum?: Thickness and purpose. A board is thin card, usually under an eighth of an inch, and sits under individual tiers inside a stack. A drum is around half an inch thick and rigid, and goes under the whole finished cake as the base it is carried and presented on. A drum holds a tiered cake; a board on its own will flex.
Why does the box height matter so much?: Because the lid touching the top of a cake ruins the finish instantly, and it is the dimension people forget to check. The box has to clear the cake, the board it sits on and a little air. A 4 inch cake on a board needs about a 6 inch box, and the commoner 5 inch boxes are sized for something shorter.
Can I use any cardboard as a cake board?: Not for anything that has to last. Ordinary cardboard absorbs fat from the buttercream, goes translucent, and softens to the point where it will not support the cake if you try to lift it. Grease resistant boards are coated to stop exactly that, and it is the one specification worth checking on a product that otherwise looks identical.
Does a square cake need a square board?: It looks better on one, and the same margin rule applies: the board should be about two inches wider than the cake in both directions. A round board under a square cake leaves the corners overhanging with nothing beneath them, which is both awkward to present and genuinely difficult to lift without damage.

Worked out for you already

A note on what this can and cannot tell you

This calculator does arithmetic on the numbers you give it. It does not know your oven, your recipe or your altitude. Figures are labelled as derived, published or trade convention, and where no honest figure exists the calculator says so instead of producing one. Researched guidance, not professional advice.