Free tool
Recipe scaling calculator
Paste your ingredients, say how many the recipe serves and how many you need, and every quantity is rescaled to an amount a kitchen can actually measure. Oven temperatures, tin sizes and cooking times are left alone, because those don’t scale with servings. Free, no sign-up, and nothing leaves your browser.
Every quantity × 1.5
Scaled
7 quantities rescaled. Oven temperatures, tin sizes and cooking times are left alone on purpose — they don’t scale with servings. Everything happens in your browser; nothing is uploaded.
How recipe scaling works
Divide the number of servings you want by the number the recipe makes. That gives you a scaling factor, and every ingredient quantity is multiplied by it. Going from 4 servings to 6 is a factor of 1.5; halving a recipe is a factor of 0.5.
The arithmetic is the easy part. The awkward part is that it produces numbers no measuring spoon has — two thirds of a cup doubled is 1.333 cups, which is a real quantity and a useless instruction. This calculator rounds every result to the nearest measure that exists in a domestic kitchen: eighths, quarters, thirds and halves.
What you should not scale
Multiplying every number in a recipe is the most common way to ruin one. These stay as written:
- Oven temperature. A doubled cake bakes at the same heat, for longer.
- Cooking and resting times. They grow, but not in proportion. Judge by the food, not the clock.
- Tin and pan dimensions. Doubling a tray bake is usually two tins, not one enormous one — depth changes how heat reaches the middle.
And a few ingredients scale arithmetically but not by taste. Salt, chilli, whole spices, yeast and raising agents all want checking by mouth once the multiplication is done.
Scaling by hand, if you’d rather
Fractions are where hand-scaling goes wrong, so convert first. Turn everything into the smallest unit in the recipe — teaspoons, or grams if you have a scale — multiply, then convert back. Three teaspoons to a tablespoon, sixteen tablespoons to a cup.
A kitchen scale removes the problem entirely. Weight scales perfectly linearly and never lands on an eighth of a spoon, which is why every professional recipe is written in grams.
Common questions
How do you scale a recipe?
Divide the servings you want by the servings the recipe makes, then multiply every ingredient quantity by that number. To take a recipe for 4 up to 6, the factor is 6 ÷ 4 = 1.5, so 2 cups of flour becomes 3 cups. The calculator on this page does that arithmetic and rounds the results to amounts you can measure.
Do cooking times change when you scale a recipe?
Usually far less than the quantities do, which is why this calculator leaves them alone. Doubling a soup does not double the simmer. What does change is the time a pan takes to come up to heat, and anything baked in a deeper tin will need longer. Check for doneness rather than trusting the clock.
Should oven temperature change?
No. Temperature stays where the recipe put it, so the calculator never touches it. If you have moved to a larger or deeper tin, keep the temperature and extend the time.
Which ingredients don't scale reliably?
Salt, chilli, strong spices, raising agents and yeast, alcohol and gelatine. Scale them, then taste and adjust — a tripled quantity of chilli is usually more than three times as hot. Baking is the least forgiving: doubling a cake is safer as two tins than one large one.
Is this calculator free?
Yes, with no sign-up and no limit. It runs entirely in your browser — nothing you paste is sent anywhere or stored.
Otto does this every time you cook
This page scales one recipe once. Otto’s servings control does it inside every recipe in your cookbook — change the number of servings and the quantities follow, snapped to the same measurable amounts, with the original always one tap away. Otto is free to download and carries no advertising.
