How recipe scaling works
Scaling a recipe is multiplication by a single factor: the target serving count divided by the original. Take a dish written for 4 and cook it for 6, and the factor is 6 ÷ 4 = 1.5 — every ingredient gets multiplied by 1.5. Halve a recipe and the factor is 0.5; triple it and it's 3. The math is simple; the place people slip is doing it line by line in their head and rounding inconsistently as they go.
This calculator scales one ingredient at a time and keeps the unit you picked, so you run each line of a recipe through the same from-and-to serving counts and trust the totals. Working by weight is what makes that trustworthy. A cup of flour can vary 20% depending on how it's scooped, and multiplying that loose measure compounds the error every time you scale. Grams don't drift — 250 g is 250 g whether you're halving or tripling — so the scaled number is as accurate as your scale.
One caution: not everything scales linearly. Ingredient weights do, but bake time, pan size, and leavening don't simply double when you double a batter. A cake scaled to twice the volume needs a wider pan and a longer, gentler bake, not the same tin crammed full. Seasoning is the other judgment call — salt, chili, and strong spices often want a little less than the raw factor suggests, so scale them, then taste and adjust.
Eggs are the awkward case, because they come in whole units. A factor of 1.5 leaves you needing one and a half eggs. The clean fix is to weigh them: a large egg is roughly 50 g out of the shell, so beat one spare egg and measure out the fraction you need. The same trick rescues any ingredient — a stick of butter, a can of tomatoes — that doesn't divide neatly.
Worked example
A sauce calls for 250 g of crushed tomatoes and serves 4; you're cooking for 6.
- Factor = target ÷ original = 6 ÷ 4 = 1.5
- Tomatoes = 250 g × 1.5 = 375 g
→ 375 g of crushed tomatoes. Run every other ingredient through the same 1.5 factor.