Recipe Scale Calculator
ガイド
Recipe Scale Calculator
Halve a cookie recipe for a smaller batch, double a soup to feed a crowd, or convert a 4-portion family dinner into a 12-person dinner party. The Recipe Scale Calculator takes any ingredient list, multiplies every quantity by your serving ratio, and prints a clean, copy-ready scaled recipe — with smart fractions like “1 1/2 cups” instead of “1.5 cups”.
It understands the way real recipes are written: mixed numbers (1 1/2), Unicode fractions (½, ⅓, ¾), ranges (2-3), pinches and dashes, and dozens of US and metric units. Lines that can’t be scaled — like “salt to taste” or section headers — pass through unchanged.
使用方法
- そこで登場するのが Original Servings the recipe currently makes (e.g. 4).
- Enter your Target Servings (e.g. 8 to double it, 2 to halve it). Or use a Quick Scale preset like 1/2, 2×, or 3×.
- Paste the ingredient list into the textarea — one ingredient per line. The “Try…” links below the box load example recipes.
- [表示モード]を選択してください Rounding mode — smart fractions for cookbook-friendly numbers, or decimals for precision.
- (Optional) Convert units to metric (g/ml) or US (cups/oz) at the same time.
- Copy the scaled list with one click, or download it as a text file.
機能
- Smart fraction rounding – Re-renders 0.333 cups as “1/3 cup”, 0.75 tsp as “3/4 tsp”, so the scaled recipe stays readable.
- Mixed and Unicode fractions – Parses “1 1/2”, “1/2”, and “½”, “⅓”, “⅔”, “¾” interchangeably.
- 20+ unit aliases – Recognises cup, c, tbsp, tablespoon, tsp, teaspoon, fl oz, pint, quart, ml, l, g, kg, oz, lb, stick, clove, slice, pinch, dash, can, package — singular and plural.
- Optional unit conversion – Switch the whole recipe between US (cups, tbsp, oz) and metric (g, ml) in one click.
- Quick Scale presets – One-click 1/3, 1/2, 2/3, 1.5×, 2×, 3×, 4× buttons.
- Range and approximate parsing – Handles “2-3 cloves garlic” and “about 1 cup brown sugar” gracefully.
- Pass-through for non-scalable lines – Headings (“For the sauce:”) and instructions (“salt to taste”) are kept verbatim.
- Show original alongside scaled – Optional inline reference so you can double-check each substitution.
- コピーとダウンロード – Grab the scaled list as plain text for shopping or sharing.
よくある質問
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Can every ingredient really be scaled linearly?
Most ingredients scale linearly: doubling a recipe means doubling each quantity. Two notable exceptions are leavening agents (yeast, baking soda, baking powder) and salt. Bread doubled in size needs slightly less yeast than 2× because more dough holds heat better and rises faster; salt scaled too aggressively can overwhelm a bigger pot before the other flavours catch up. For batches more than 3× larger or smaller, professional bakers reduce leavening and salt by 5-10% as a starting point and adjust by taste.
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Why does my favourite cookbook use weight (grams) instead of volume (cups)?
Volume measurements are inconsistent because how tightly you pack flour or sugar changes its weight by up to 25%. One "cup" of flour can be anywhere from 100 g to 150 g depending on whether you scoop, sift, or spoon it. Weight measurements remove that ambiguity. Professional bakers and most European cookbooks use grams for this reason, especially for baking where small ratios matter.
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What is the difference between fluid ounces and weight ounces?
Fluid ounces (fl oz) measure volume — how much space a liquid takes up. Weight ounces (oz) measure mass — how heavy something is. They are the same number only for water at room temperature, where 1 fl oz of water weighs 1 oz. Honey, for example, weighs about 1.5 oz per fl oz because it is denser than water. This is why dry ingredients in US recipes are usually given in cups (volume), but their gram equivalents differ between flour, sugar, and rice.
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Why does cooking time not scale with serving size?
Cooking time depends on the geometry and thermal properties of the food, not the total quantity. A roast that is twice as heavy is not twice as long along any dimension — it is roughly 1.26× larger in every direction (cube root of 2). Heat penetrates from the surface, so cook time scales with thickness, not weight. A doubled pot of soup, however, takes longer to come to a boil because there is more thermal mass to heat — but once boiling, the simmer time is identical. As a rule, increase oven and stovetop times only modestly when scaling up; check doneness by temperature or texture, not the clock.
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Why are recipes traditionally written for 4-6 servings?
Standard 8-inch and 9-inch baking pans, 12-cup muffin tins, and 9×13 casserole dishes were sized for postwar US households of 4-6 people, and recipe formats were standardised around them by mid-20th-century test kitchens. A recipe for 4 also divides cleanly: half (2), third (1.33), quarter (1), or double (8). When you scale beyond this comfort zone, you often need a different pan size — a doubled cake batter in the same 9-inch pan will overflow or bake unevenly.
