How much buttercream do I need for an 8 inch (20 cm) cake?

About 925 g (roughly 4.3 cups) for an 8 inch (20 cm) round tier 4 inches (10 cm) tall: that covers a crumb coat, a sharp final coat, two standard filling layers and a 10% margin so you do not run out mid-coat. A rustic or heavily piped finish needs more.

How much buttercream do I need for a 6-8-10 inch (15-20-25 cm) three tier wedding cake?

Plan on about 2,825 g - roughly 13 cups, or about 2.5 batches of the LAYER'D studio buttercream (200 g liquid egg whites, 335 g superfine sugar, 600 g butter). That includes crumb coats, sharp final coats, standard fillings on three-layer tiers and a 10% insurance margin.

What ratio of chocolate to cream do I use for a ganache drip?

Dark chocolate (around 54%) drips at about 1 part chocolate to 1 part cream by weight. Milk chocolate needs about 2 to 1 and white chocolate about 2.5 to 1, because they carry less cocoa solids. An 8 inch (20 cm) drip uses about 150 g of finished ganache - always test the consistency on the back of a chilled cake first.

How do I scale a recipe to a different pan size?

Multiply every ingredient by the ratio of the pan areas (times the number of layers, if that changes too). Moving an 8 inch (20 cm) round recipe to a 10 inch (25 cm) round pan means multiplying everything by about 1.56. Bigger pans bake longer at the same temperature, so start checking early - and be careful scaling leaveners like baking powder much past double.

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Batch Math

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The calculators need JavaScript to run — but the reference table further down this page covers the most common tier combinations, no script required.

Everything above is worked out from your cake already. Open any calculator below to fine-tune it — change a pan, a filling depth, a recipe — and the numbers above follow.

1 Cake batter

How much sponge this cake needs — totalled by area from your tiers & layers.

3 Fillings

Compotes, crémeux and montées in grams, from your tiers and filling layers.

2 Ganache & drip

Chocolate and cream in grams, at the right ratio for your chocolate.

4 Buttercream quantity

Crumb coat, final coat and filling in grams, margin stirred in — one batch = the LAYER’D studio SMBC (~1,140 g), free in the Recipe Library.

Buttercream guide — the classic combinations

What these numbers assume The numbers below assume 4-inch-tall (10 cm) round tiers with a sharp minimal finish, a crumb coat, and the 10% insurance margin — the same defaults the calculator starts from. Coats only is your number when the layers are filled with compote, crémeux or ganache (those are not buttercream — the Fillings calculator above handles them). With buttercream filling adds standard-thickness buttercream beds between three cake layers per tier; cups and batches follow that column. One batch = the LAYER’D studio buttercream — 200 g liquid egg whites, 335 g superfine sugar, 600 g butter — about 1,140 g.

Buttercream quantities for common cake tier combinations
Cake	Coats only	With buttercream filling	Cups (approx.)	Batches
6" / 15 cm round, single tier	~375 g	~575 g	2.7	0.5
8" / 20 cm round, single tier	~525 g	~925 g	4.3	0.8
10" / 25 cm round, single tier	~725 g	~1,325 g	6.2	1.2
6" + 8" two tier (15 + 20 cm)	~900 g	~1,500 g	7.0	1.3
8" + 10" two tier (20 + 25 cm)	~1,250 g	~2,250 g	10.5	2.0
4" + 6" + 8" three tier (10 + 15 + 20 cm)	~1,125 g	~1,825 g	8.5	1.6
6" + 8" + 10" three tier (15 + 20 + 25 cm) — the classic	~1,625 g	~2,825 g	13.1	2.5
6" + 8" + 10" + 12" four tier (15–30 cm)	~2,550 g	~4,625 g	21.5	4.1

Taller tiers, rustic texture and heavy piping all add volume — use the calculator above for anything off the standard grid.

5 Recipe pan-scaling

A stand-alone utility: your recipe was written for pans you don’t own — we do the multiplication (paste the ingredient list and it scales too).

LAYER’D TIP Bigger pans bake longer at the same temperature — never hotter. Keep the oven where the recipe says and start checking a good ten minutes earlier than you think you need to; the skewer is the boss, not the timer.