Recipe maths

Recipe Scaling Calculator

Halve the cookies, double the loaf, or move a cake into a different tin. Type or paste the ingredient list, say how much bigger or smaller the batch should be, and every line comes back rewritten in grams and in US cups — with the awkward fractions flagged so nothing gets guessed at the counter. Bread formulas keep their baker's percentages, because every ingredient is multiplied by the same number. All of the arithmetic happens in your browser; nothing is uploaded or saved.

Your ingredient list never leaves this device. Close the tab and it is gone.

What you are scaling

Scale by

Servings, cookies, muffins or loaves — whatever the card counts.

The batch you actually want to end up with.

Keep the amounts as the recipe writes them — 500 g, 1 1/2 cups, 2 eggs, 4 to 4 1/4 cups. Fractions, decimals and mixed numbers all work. A line with no amount at the front, like "salt to taste", is carried through untouched.

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The scaled recipe

Paste your ingredient list, choose how to scale it, and pressScale the recipe. The rewritten amounts appear here — nothing is sent anywhere.

How to scale a recipe

  1. Say what changes. Servings if the card gives a yield, a multiplier if you just want half or double, and a pan if you are moving a cake or a focaccia into a different tin. A pan swap compares the base area, so a 9-inch round tin takes about 1.27 times the batter of an 8-inch one.
  2. Paste the ingredients exactly as they are written. One ingredient per line, amounts at the front. Weights with a thousands comma, cups as fractions and "4 to 4 1/4 cups" style ranges are all read the way a recipe card writes them.
  3. Press Scale the recipe. Each line comes back with the new amount, the gram weight where one can be worked out, and the US cup measure beside it.
  4. Read the flags before you bake. Amounts that do not land on a standard cup or spoon are listed with the closest measure, so you can decide whether to round, measure by weight, or leave that ingredient where it was.

Reading the results

Scaling is multiplication, and multiplication is honest: every line is multiplied by the same factor, so the relationships between the ingredients do not move. That is why the baker's percentage column is identical before and after scaling. In a bread dough, 1,000 g of flour with 650 g of water is 65% hydration whether you bake one loaf or three; the numbers grow, the formula stays put.

The cups column is an estimate. A US cup of flour is about 120 g when it is spooned and levelled, sugar about 200 g, honey about 336 g — a cup is a volume, and every ingredient fills it with a different weight. The figures here use each ingredient's standard baking density, so they are close enough for a shopping list and a sanity check, but the gram column is the one to bake from.

Densities used for the cup estimates
IngredientGrams per US cup
Bread or all-purpose flour120 g
Granulated sugar200 g
Packed brown sugar213 g
Butter227 g
Milk240 g
Honey336 g

What scaling cannot fix

  • Baking time is not linear. A doubled batch in the same tin bakes longer at the same temperature; a thinner layer bakes faster. Start checking at the original time and trust the cue the recipe names — colour, spring, internal temperature — rather than the clock.
  • Pan depth is not part of the comparison. A pan swap here matches base area. If the batter ends up deeper or shallower than before, the bake changes even though the arithmetic is right.
  • Leaveners and salt do not always scale straight. Chemical leaveners, instant yeast and salt are usually scaled with everything else, but very large changes or a different pan can want a nudge. This calculator does not decide that for you — it shows the straight multiplication and the baker's percentage so you can see what you are working with.
  • It does not fetch a recipe from a link. There is no scraping and no network call: paste the ingredients you have in front of you.
  • It does not weigh or measure anything. Counts such as "2 eggs" stay counts, and nothing here knows how you fill your cup.

Questions about scaling recipes

How do I halve a recipe that calls for 3 eggs?

The arithmetic here gives you 1 1/2 eggs, and that is the honest answer — the calculator will not pretend an egg splits evenly. In the kitchen, beat the third egg in a small bowl, weigh it, and use half; a large egg is about 50 g without the shell, so half is roughly 25 g. If the recipe uses eggs mostly for richness, one large egg plus a tablespoon of milk gets you close enough for a cookie or a muffin.

Can I just double every ingredient?

For weights and volumes, yes — that is exactly what this calculator does, and it is reliable for flours, sugars, butter, milk, water and starter. Two things stop being pure multiplication. Chemical leaveners, instant yeast and salt often sit a little under or over a straight double once a batch gets very large, so check the baker's percentage column rather than assuming. And baking time never doubles: a doubled batch in the same tin needs longer at the same temperature, while a thinner layer needs less.

How do I scale a recipe for a different pan?

Pan size is compared by base area, which is what this calculator does. An 8-inch round tin is about 50 square inches and a 9-inch round is about 64, so the larger tin takes roughly 1.27 times the batter. The comparison assumes the batter ends up at a similar depth — a 9-inch tin filled with 1.27 times the batter is a slightly thinner cake than the original, which bakes a little faster. If the depth changes a lot, treat the timing as a fresh question and watch the bake.

Why do the baker's percentages stay the same after scaling?

Because every ingredient is multiplied by the same factor, so the ratios between them cannot move. A dough at 65% hydration is 65% hydration whether you mix 1,000 g of flour or 500 g; the totals change and the formula does not. The baker's percentage column is there so you can see the formula you are actually baking and check it against the recipe's own numbers.

Does scaling a sourdough recipe change how long it takes to rise?

Slightly, yes. The starter percentage is unchanged, so the dough ferments at the same rate per gram of flour, but a bigger mass holds its heat a little longer and a smaller one cools faster, so bulk fermentation can drift by a while either way. Keep the recipe's starter percentage and judge bulk by the dough — volume, doming, jiggle — rather than by the clock on the card.

Where do the cup measurements come from?

From standard baking densities: about 120 g per US cup for flour, 200 g for granulated sugar, 227 g for butter, 240 g for milk and 336 g for honey. A cup is a volume and every ingredient fills it with a different weight, so those cup figures always carry the word est. The gram column is the one to bake from — and if you want a single ingredient converted in both directions, the cups to grams converter does that on its own.

Scale something from the Bakehouse

Every recipe here prints grams first and cups alongside, so a scaled list and the original card read the same way. Pick a recipe, work out the batch, then bake it: