The 1-2-3-4 Cake Rule, Explained
One cup butter, two cups sugar, three cups flour, four eggs. It is one of the oldest cake formulas in English baking and it still works. Here is why, how to scale it to a tin you actually own, and what it costs per slice once you do the arithmetic.
The formula
The traditional version is by volume: 1 cup butter, 2 cups sugar, 3 cups flour, 4 eggs, plus raising agent, liquid and flavouring. In metric weights, a workable equivalent is roughly:
Converting to weight is worth doing once. A cup of flour varies by up to 20% depending on whether it was scooped or spooned, which is enough to change the crumb — and more than enough to make costing meaningless.
Why it works
The ratio balances the four structural jobs in a cake: fat for tenderness, sugar for moisture and browning, flour for structure, egg for lift and binding. Sugar exceeding flour by weight puts it in the high-ratio family, which is why it stays moist and takes decoration well.
It is a starting point, not a specification. Traditional formulas assume a particular flour and a particular oven; yours will differ.
Scaling it to your tin
Cake batter scales with tin area (for the same depth), not diameter. Two 8-inch tins are not equivalent to one 16-inch tin — a 16-inch has four times the area of an 8-inch.
- Work out the area of your tin: πr² for round, length × width for square.
- Divide by the area the formula was written for.
- Multiply every ingredient by that factor.
- Do not scale the baking time by the same factor — a wider, same-depth cake bakes in similar time; a deeper one takes considerably longer.
Our guide to scaling recipes covers the parts that do not scale linearly.
What it costs per slice
The useful exercise for anyone selling: cost the formula at real pack prices, divide by sellable slices, and compare with what you charge. Butter is usually 55–65% of the ingredient cost in this formula, which means butter price movements hit this cake harder than most.
Run yours through the free recipe cost calculator — batch cost, cost per slice and a recommended sell price, no account needed. Then read pricing cakes for profit for what to do with the number.
Frequently asked questions
What is the 1-2-3-4 cake rule? One part butter, two sugar, three flour, four eggs — traditionally by cup measure, better converted to weights for consistency.
Should I use cups or grams? Grams, if you sell. Cup measures vary enough between people to change both the result and the cost per unit.