Recipe Scaler Calculator
Scale ingredient amounts based on serving size change.
Enter serving counts.
Guide to Recipe Scaling
How to convert ingredients?
When scaling a recipe, remember to maintain proportions. If you double the amount, multiply all ingredients by two. Use a calculator to ensure accurate quantities. Some ingredients are harder to convert - for example, you can halve an egg but small ingredients like salt or spices are better added to taste after cooking.
Cooking time with larger batches
When increasing servings, cooking time often extends. More ingredients in a pot means longer time to reach boiling temperature. Soups and stews usually require 10-20 minutes longer. For baking, increase time by about 15-20% and check halfway through. The baking dish should be large enough for the batter to spread.
Scaling down
Reducing a recipe is harder than increasing it. With very small quantities, some ingredients are difficult to measure. You can use a whole egg and reduce another ingredient. For spices, start with less and add to taste. Remember that small batches cook faster - reduce cooking time by about 20%.
What to scale and what not to?
Scaling works well for soups, stews, sauces, and dishes where everything is mixed. It's harder for dishes where ingredients are layered - for baking, proportions are critical. More isn't always better - some recipes are designed for specific dishes and larger quantities may not work. Check if the recipe has additional scaling notes.
Scale a cake tin by area, not by diameter
Multiplying every ingredient by the same number works for most cooking. Baking is where it breaks, and the usual reason is the tin: going from a 20 cm round to a 23 cm round looks like a 1.15× step, but the area grows 1.32×. Scale by the diameter and the cake comes out 13% thin.
How it works
- Multiplies ingredient quantities by a serving ratio, converting awkward fractions into workable amounts.
- Scales tin sizes by area rather than by width, which is where most scaling errors originate.
- Flags the ingredients and steps that do not scale proportionally.
ingredient ratio = new servings ÷ original servings round tin area = π × (diameter ÷ 2)² tin ratio = new area ÷ old area 20 cm → 23 cm is 1.15× across but 1.32× by area
Worked example
Moving a recipe written for a 20 cm round tin into a 23 cm one.
- diameter ratio: 23 ÷ 20 = 1.15
- area of 20 cm tin: π × 10² = 314 cm²
- area of 23 cm tin: π × 11.5² = 415 cm²
- true ratio: 415 ÷ 314 = 1.32
- scaling by 1.15 instead leaves the tin 13% under-filled
The correct multiplier is 1.32, not 1.15. A 20 cm square tin holds 400 cm² against the round tin's 314 — 27% more — so swapping shapes at the same nominal size is itself a scaling decision.
Reading the result
- Baking time follows depth, not volume. A doubled batch spread across two tins bakes in roughly the original time; the same batch in one deeper tin can take 50% longer and will often be raw in the middle when the edges are done.
- Salt, spices and chilli scale sub-linearly in practice. Doubling them usually overshoots, so scale to about 1.5× for a doubled batch and adjust at the end, where you can still correct upward.
- Leavening is the exception that punishes both directions. Too little and the crumb is dense; too much and the structure rises fast then collapses. Scale it proportionally and measure it precisely.
- Egg quantities land on fractions. Beat a whole egg, weigh it, and use the fraction you need — roughly 50 g per large egg — rather than rounding, which shifts both liquid and binding.
Common questions
- Can I just double everything?
- For stews, sauces and most stovetop cooking, essentially yes. For baking, scale the tin by area, hold seasoning back to around 1.5×, keep leavening proportional and expect the timing to change with depth rather than with quantity.
- What if I only have a different-shaped tin?
- Compare areas rather than nominal sizes. A 20 cm square is 400 cm² and a 20 cm round is 314 cm², so the square needs 27% more mixture to reach the same depth — and depth is what sets the baking time.