Tool
Recipe Scaler
Scale a recipe up or down, or to a target number of servings, with smart fraction rounding (1½ cups, never a raw 1.4732 cups) built right in.
Recipe Scaler
Scale factor: 1.500x
2¼
(exact: 2.2500)
Doubling a recipe sounds like simple multiplication until you actually try it: 2/3 cup times 1.5 is 1.4732 cups on a calculator, and no measuring cup has a mark anywhere near that. Recipe scaling isn't a math problem so much as a rounding problem — the challenge is landing on a fraction a real measuring cup or spoon can actually hit.
This tool scales a quantity by a target factor (or from an original serving count to a target serving count) and rounds the result to the nearest practical kitchen fraction — halves, thirds, quarters, and eighths, the denominators that actually appear stamped on US measuring tools — instead of handing back a decimal that's technically correct and practically useless.
It treats weight and volume differently on purpose: volume quantities (cups, tablespoons, teaspoons) round to a kitchen fraction, while weight quantities (grams, for a kitchen scale) round to the nearest tenth of a gram, because a digital scale reads fine decimals, not eighths.
How the Recipe Scaler works
Enter a recipe's original quantity and either a scale factor directly (e.g. 1.5 for a recipe-and-a-half) or an original and target serving count, and the tool computes servingsScaleFactor = target ÷ original, then multiplies your quantity by that factor.
For volume units, the raw scaled decimal then goes through a fraction-rounding pass: it tests denominators of 2, 3, 4, and 8, finds whichever one lands closest to the actual decimal value, and returns that as a fraction (and, where one exists, the matching Unicode symbol like ½ or ¾) rather than showing 1.4732.
The rounding is intentionally conservative — if the decimal is within about 1/32 of a whole number, it rounds straight to that whole number instead of returning an oddly precise eighth, since no one is measuring in thirty-seconds in a home kitchen.
Worked example: scaling 2/3 cup up by 1.5×
2/3 cup (0.667) × 1.5 = 1.0 cup exactly in this case — a clean result. But scale a recipe that calls for 3/4 cup by 1.5× instead: 0.75 × 1.5 = 1.125. The tool tests 2, 3, 4, and 8 as denominators against 0.125 (the fractional part after the whole number 1) and finds that 1/8 is an exact match, returning "1 1/8 cups" rather than "1.125 cups."
Now scale 1 1/3 cups by 0.75× (shrinking a recipe by a quarter): 1.333 × 0.75 = 1.0 cup — again clean. The tool isn't always this tidy; scaling 1/3 cup by 1.75× gives 0.583, which the tool rounds to the nearest eighth (0.583 is closer to 4/7 than any eighth, but among the four allowed denominators 5/8 = 0.625 and 1/2 = 0.5 are the closest options — the tool picks whichever of those has the smaller error, in this case 1/2).
Edge cases this tool handles correctly
- Very small scale-downs
- Scaling a quantity down to something smaller than 1/32 of the original rounds to zero — the tool won't return a fraction so small it's unmeasurable, since at that point the ingredient is effectively omitted from the scaled recipe.
- Weight vs. volume ingredients
- If you're scaling a quantity given in grams (common in recipes converted with the Ingredient Converter), the tool rounds to the nearest 0.1g instead of a kitchen fraction, since a scale — not a measuring cup — is what reads that value.
- Egg counts and other whole-item quantities
- Ingredients measured by count (eggs, cloves of garlic) round to the nearest whole number rather than a fraction — half an egg isn't a real kitchen instruction, so the tool flags count-based ingredients separately from volume and weight ones.
Frequently asked questions
Why not just show the exact decimal?
Because no standard US measuring cup or spoon is marked in arbitrary decimals — the tool's whole purpose is converting a mathematically correct number into one you can actually measure with the tools in a home kitchen.
Does scaling a recipe up always work perfectly?
Scaling volume and weight ingredients is reliable math, but scaling doesn't account for things like pan size, bake time, or leavening behavior at a much larger volume — very large scale-ups (tripling or more) often need adjustments this tool doesn't attempt to predict.
What if I want sixteenths instead of eighths?
The tool deliberately stops at eighths because that's the finest gradation marked on standard US measuring spoons and cups — a sixteenth-cup measurement isn't something most kitchens can act on precisely anyway.
Can I scale by a serving count instead of a multiplier?
Yes — enter the recipe's original and target servings and the tool computes the scale factor for you before applying it to each quantity.