Recipe Scaler

How the Recipe Scaler works

Each line is read on its own: a leading amount (including "1 1/2", "1½" and "2–3"), then a unit if there is one, then everything else as the ingredient and its prep note. Whatever it can't read, it leaves exactly as you typed it and says so. Nothing is ever silently dropped — the list you copy is always the same length as the list you pasted, because a scaler that quietly loses a line is worse than no scaler, since you'd have no reason to check.

Volume amounts are rounded to the nearest practical kitchen fraction: the tool tests denominators of 2, 3, 4, and 8 and keeps whichever lands closest, so you get "1⅛ cups" instead of "1.125 cups". Weights are treated differently on purpose — a digital scale reads whole grams, not eighths, so gram amounts round to a number you can actually chase on a scale. Counts round to the nearest quarter, because half a can of tomatoes is a real instruction and half an egg mostly isn't.

The "scale to what I have" mode is the one that needs real data behind it. If your constraint is in the same kind of unit the recipe uses, it's a straight ratio. If you're crossing weight and volume — 350 g against a recipe written in cups — the tool converts through that specific ingredient's own sourced grams-per-cup density, the same figure the Ingredient Converter uses. Where the site has no sourced density for the ingredient, the tool says so and declines rather than assuming a generic one.

Two categories are deliberately left alone. "Salt to taste" and "a pinch of nutmeg" are instructions, not measurements, and multiplying them produces nonsense; they pass through untouched. Leaveners, yeast, salt and strong extracts do get scaled, because that's the arithmetic you asked for — but they're flagged, because a doubled cake genuinely doesn't want exactly double the baking powder.

Worked example: a cake for six when the recipe serves four

Paste the list, choose "by servings", and enter 4 and 6 — a factor of 1.5. A line reading "2 cups all-purpose flour" becomes 3 cups, clean. "3/4 cup whole milk" becomes 1.125 cups, which the tool returns as 1⅛ cups, because that's a jug marking you can find. "2 large eggs" becomes 3 — a genuinely lucky case, since 1.5 eggs would have needed a decision from you rather than from the tool. And "1 1/2 tsp baking powder" becomes 2¼ tsp with a flag on it: correct multiplication, but at 1.5× a cake this is where you'd sensibly round down rather than up.

Now the constraint case, which runs backwards. The recipe wants 3 cups of all-purpose flour and the bag has 350 g left. Three cups of all-purpose flour at its sourced 120 g per cup is 360 g, so 350 g is a factor of 0.97 — you are ten grams short of the full recipe, not a third short, and the honest answer is to scale everything by 0.97 and carry on. Ask the same question with bread flour in the bag and the answer shifts, because bread flour is 127 g a cup and three cups is 381 g. The density is doing real work here; a generic "a cup of flour is 120 g" would have quietly given you the wrong factor for the wrong flour.

Edge cases this tool handles correctly

Lines the parser can't read

A line with no recognisable number — "Zest of one lemon", a stray instruction that got copied in with the list — is passed through unchanged and labelled as such under the result. It is never guessed at and never removed, so you can see at a glance which lines still need your own judgement.

Ranges like "2–3 tablespoons"

Both ends of a written range are scaled and the range is preserved, because the range was the recipe author telling you the amount is a matter of taste. Collapsing it to a single number would throw away information you were given on purpose.

Very large scale-ups

Past about 3× the arithmetic stays right and the baking stops matching it: leavening, evaporation, and the depth of batter in the pan all stop behaving proportionally. The tool flags the ingredients most affected, but a tripled cake is genuinely a different bake, not the same bake made bigger — and the pan you use for it is the Pan Size Converter's problem.

Eggs and other whole-item ingredients

Counts round to the nearest quarter rather than to a whole number, which sounds odd until you halve a three-egg recipe: the honest answer is 1.5 eggs, and the practical answer is to beat two and use half by weight. Rounding silently to 2 would have hidden the decision from you.

Frequently asked questions