Recipe Scaler
Paste any recipe, change the serving count, and get scaled ingredient amounts with smart fraction display (1/2, 1/3, 3/4 instead of ugly decimals).
Recipe Scaler
How to use the Recipe Scaler
Paste the recipe ingredients
Copy ingredients from any cookbook, blog, or app and paste them into the left panel — one ingredient per line. The scaler parses the leading quantity from each line (supports integers, decimals, and fractions: "2", "2.5", "1/2", "2 1/2" all work). Anything without a leading number (like "salt to taste" or section headers) gets passed through unchanged.
Set original and new serving counts
"Original servings" is what the recipe was written for. "New servings" is how many you want to make. Cutting a 4-serving recipe to 2? Set 4 → 2. Scaling up a 6-serving recipe for a dinner party of 12? Set 6 → 12. The math handles any ratio — scaling a 1-serving recipe to 17 servings just works.
Read the scaled output in cooking-friendly fractions
Numbers get rounded to common kitchen fractions: 1/16, 1/8, 1/6, 1/5, 1/4, 1/3, 3/8, 1/2, 5/8, 2/3, 3/4, 5/6, 7/8. So a scaled "1.5" becomes "1 1/2", "0.33" becomes "1/3", "1.75" becomes "1 3/4". Decimals only appear when no clean fraction matches within 5% tolerance.
Mind the seasoning + spice scale break
The bulk ingredients (flour, butter, sugar, liquids) follow the scale factor. Salt, spices and aromatics are where culinary texts tell you to be careful: Gisslen's Professional Cooking notes that seasonings and spices may have to be cut back when a recipe is converted. There is no fixed multiplier for this. The kitchen rule of thumb is to add less than the full scaled amount, taste, then add the rest. The scaler does straight linear math, so treat its seasoning lines as an upper limit. Yeast, baking powder and baking soda need care too; see the FAQ for baking-specific guidance.
Recipe scaling — why linear math fails for spices, yeast, and baking soda
Scaling a recipe is mostly arithmetic: multiply every ingredient by the scale factor (new servings / original servings), which culinary textbooks call the recipe conversion factor. For most ingredients this works: flour, milk, butter, sugar, oil, water, eggs, meat and vegetables all follow the factor. Where linear scaling breaks down is in three specific categories: seasonings (salt, herbs, spices), leavening agents (yeast, baking soda, baking powder), and surface-area-dependent items (oils used for greasing pans, eggwash quantities, breading depth). Knowing where to deviate from the math is the difference between a doubled recipe that tastes right and one that's painfully over-salted or won't rise.
Seasoning: start below the factor, then taste
Salt, pepper, garlic, ginger and dried herbs are the ingredients most likely to go wrong when you multiply. Wayne Gisslen's Professional Cooking lists seasoning among the problems in converting recipes, noting that seasonings and spices may have to be cut back, and the open textbook Basic Kitchen and Food Service Management advises increasing them with caution: under-season, then adjust just before serving. There is no agreed multiplier. The kitchen rule of thumb is simply to add less than the full scaled amount, taste, and add more if it needs it. That is why professional kitchens taste and adjust seasoning at the end rather than trusting the math, even when the underlying recipe is precise.
Linear math works for flour, butter, and sugar — but not for salt, spice, or yeast. Scale the bulk, then taste and adjust the seasoning by hand. The math gets you to the ballpark; your palate gets you home.
Baking has its own rules
Baking is chemistry as much as cooking, and it is less forgiving when scaled. Yeast keeps multiplying through the rise, so how fast a dough rises depends on its temperature and size as well as on how much yeast went in. Scale it with the factor, then judge the dough by how it looks rather than by the clock; some bakers deliberately use a little less in a big batch for a slower, more flavourful rise. Baking powder and baking soda are best scaled with the factor and tried on a small batch before a big bake. Pan size matters as much as the ratios: doubling a recipe in the same-sized pan changes the depth of the batter, and with it the baking time and the crumb. The safest scale-up is often to make several batches in the pan size the recipe was written for.
The ASEAN home-cooking angle
Recipe scaling works the same everywhere, but a few ASEAN home-cooking habits are worth knowing. Rice: when you cook for a big family gathering (Hari Raya, Chinese New Year, Diwali, Christmas, Lebaran), the limit is often the rice cooker's capacity rather than the arithmetic, so plan in batches the cooker can take. Curry pastes and sambals: chilli heat and aromatics build quickly, so add the scaled paste for a bigger rendang in stages and taste as you go. Soy sauce, fish sauce, kecap manis: treat them like salt and season below the factor first. Pandan leaves, lemongrass, galangal, kaffir lime leaves: their strength varies from bunch to bunch anyway, so go by taste. The calculator does the bulk math; your tongue and your family's recipes do the seasoning.
Linear until it is not: salt, yeast, pan size and cups that disagree
Recipe scaling is mostly linear arithmetic: multiply every ingredient by the conversion factor (new servings ÷ original servings). The bulk ingredients, such as flour, butter, sugar, liquids and meat, follow it.
Salt and spices are the classic exception. Gisslen's Professional Cooking notes they may have to be cut back when a recipe is converted, so season below the factor and taste.
Yeast is a living organism that keeps multiplying through the rise, so rise time depends on temperature and dough size, not only on how much you added. Watch the dough, not the clock.
Baking is the hardest thing to scale because pan size matters as much as ingredient ratios. Doubling in the same pan changes baking time, temp, and texture.
The kitchen fractions humans use intuitively — 1/2, 1/3, 1/4, 3/4, 1/8 — match the markings on standard US measuring cups and spoons.
Professional kitchens measure by weight (grams), not volume (cups), because how firmly flour is packed changes what a cup weighs. King Arthur Baking's chart puts a cup of all-purpose flour at 120 g.
1 US measuring cup = 237 mL (NIST Handbook 44), though US nutrition labels round it to 240 mL (21 CFR 101.9). The metric cup of Australia, New Zealand and much of Southeast Asia is 250 mL (NSW Health). The UK imperial cup is neither: it is 284 mL, half an imperial pint. Modern British recipes mostly weigh rather than scoop, so a British "cup" usually means the 250 mL one, but an older book may mean 284 mL, about 14% more.
1 tbsp = 3 tsp almost everywhere (15 mL and 5 mL in NIST Handbook 44), but not in Australia, where the tablespoon is 20 mL (NSW Health) and therefore four teaspoons. It is the conversion most often assumed universal, and the one that quietly adds a third to every spoonful of baking powder in an Australian recipe.
Halving a recipe with "1 egg" is a classic scaling problem. Solutions: beat the egg first, weigh out half; or use 1 yolk for half; or scale to 0.5× of all eggs and accept "almost half" precision.
Cooking time doesn't follow the factor. A bigger roast or a deeper pan takes longer, but not in proportion, and a different pot or oven changes it again. Go by a thermometer or a doneness test, not by multiplying the time.
Frequently Asked Questions
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Because seasoning is judged by taste, and culinary texts flag it as one of the things that does not convert cleanly: Gisslen's Professional Cooking notes that seasonings and spices may have to be cut back when a recipe is converted. No reliable multiplier exists. The kitchen rule of thumb is to add less than the full scaled amount, taste, then add the rest. The bulk ingredients (flour, butter and so on) scale linearly through the calculator; adjust seasoning by taste after the first batch.
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Start with the scaled amount, then let the dough tell you. Yeast multiplies during fermentation, so how fast a dough rises depends on its temperature and size as much as on the yeast you added, and a large batch will not necessarily rise on the original schedule. Some bakers deliberately use a little less yeast when scaling up, for a slower, more flavourful fermentation. When halving, err on the low side: too little yeast only means a longer rise, while too much can over-proof the dough quickly.
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Small changes usually work in the same pan, though the baking time may shift, so check early and test for doneness. For bigger changes you need a larger pan and an adjusted baking time (often a lower temperature and a longer time for deeper batters), or you should make several batches at the original pan size. Doubling a cake in the same pan typically produces a denser, undercooked center because heat transfer doesn't keep up. For cookies and individual pastries, scaling is safer because each piece is independent.
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Three options: (1) Beat the egg in a small bowl, then use a scale or measuring spoon to take half (~25g of beaten whole egg). (2) Use just the yolk for half scaling (~17g) — works for binding, doesn't give the leavening of whites. (3) Round up to 1 whole egg and accept the recipe is slightly egg-heavy — usually fine for cookies, frittatas, and casseroles. For recipes where egg ratio is critical (souffles, mayonnaise), use option 1 with a scale.
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Not in proportion. Cooking time depends on the size and shape of each piece and on the pan, not on the total quantity: a doubled stew in a wider pot may need little extra time, while a roast twice the weight takes longer, but not twice as long. Changing the pot, pan or oven changes it again. Use a thermometer for internal doneness rather than trusting time. For boiling / simmering on the stovetop, recovery time after adding cold ingredients matters more than scale — preheat the larger pot longer.
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Yes — any recipe with one ingredient per line works. The parser handles integers (2), decimals (2.5), fractions (1/2), and mixed numbers (2 1/2). Lines without a leading number (like "Salt to taste" or section headers like "FOR THE SAUCE:") pass through unchanged. If your source uses unusual notation (e.g. "Two and a half cups"), edit it to numeric form first. The tool doesn't understand spelled-out numbers or units in non-Latin scripts.
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Because cooking happens in cups and spoons, not decimals. The output uses common kitchen fractions (1/8, 1/4, 1/3, 1/2, 2/3, 3/4 etc.) that match the markings on standard US measuring cups and spoons. If the scaled value doesn't fall within 5% of a common fraction, the output falls back to a decimal. This makes it easy to read while measuring — "1 1/2 cups" is what you'll actually measure, not "1.5 cups".
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Because the weight of a cup depends on how the ingredient is packed. Sifted flour vs scooped flour vs spooned flour all give different gram weights for the same "1 cup" measurement. Weight is exact: 120g of flour is 120g of flour regardless of how it was packed. Professional bakeries weigh everything; serious home bakers do too. For consistent results when scaling, convert volume recipes to weight first (King Arthur Baking and Joy of Cooking both publish ingredient density tables).
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No. All scaling runs entirely in your browser via JavaScript. There's no server roundtrip — open DevTools → Network and confirm zero outbound requests as you change inputs. Your recipes stay on your device. Safe for proprietary family recipes, restaurant test menus, or any culinary IP that shouldn't leave your machine. Close the tab and nothing remains.
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Yes — the scaler is unit-agnostic and only reads the leading numeric quantity. It works for cups, tablespoons, grams, milliliters, ounces, ladles, "to taste" annotations, or any other unit-of-measure. The caution about seasoning matters even more in ASEAN, South Asian and Middle Eastern cooking, where aromatics carry the dish: add chillies, lemongrass, ginger, garlic, cumin and cardamom in stages and taste. For rice, the grain follows the factor, but check the water against your rice cooker's markings rather than multiplying it, especially for large batches.
Method & sources
How it computes
Multiplies every leading quantity in the pasted ingredient list by a recipe conversion factor = new servings ÷ original servings (the textbook RCF method), then renders the result as the nearest common kitchen fraction (1/16 … 7/8) within a 5% tolerance, falling back to decimals. Lines without a leading number pass through unchanged. Seasoning, leavening and cooking time are deliberately NOT adjusted — the page says why.
What this tool implements
- Recipe conversion factor RCF = desired yield ÷ original yield, applied linearly to every quantity (Culinary Institute of America; Gisslen)
- Textbook caution carried onto the page: seasonings, leavening, cooking times and equipment do not convert proportionally — adjust by taste and test, not by the factor
- Fraction display snaps to 1/16, 1/8, 1/6, 1/5, 1/4, 1/3, 3/8, 2/5, 1/2, 3/5, 5/8, 2/3, 3/4, 4/5, 5/6, 7/8 within ±0.05
- Cup sizes stated on the page: US measuring cup 8 fl oz = 237 mL (NIST HB 44), FDA labelling cup 240 mL (21 CFR 101.9), metric cup 250 mL and Australian tablespoon 20 mL (NSW Health), imperial cup = ½ imperial pint = 284 mL (Weights and Measures Act 1985)
Sources
- Culinary Institute of America. The Professional Chef. 9th ed. Hoboken, NJ: Wiley; 2011. Recipe conversion factor (desired yield ÷ original yield).
- Gisslen W. Professional Cooking. 9th ed. Hoboken, NJ: Wiley; 2018. "Recipe conversion" and "Problems in converting recipes".
- NIST Handbook 44 (2026 ed.), Appendix C, General Tables of Units of Measurement — 1 measuring cup = 8 fluid ounces = 237 mL. https://doi.org/10.6028/NIST.HB.44-2026
- 21 CFR 101.9(b)(5)(viii) — for nutrition labelling a teaspoon means 5 mL, a tablespoon 15 mL, a cup 240 mL. https://www.law.cornell.edu/cfr/text/21/101.9
- NSW Health (Central Coast Local Health District). The Pantry Staples — 1 tablespoon = 20 mL, 1 teaspoon = 5 mL, 1 cup = 250 mL. https://www.cclhd.health.nsw.gov.au/wp-content/uploads/ThePantryS…
- King Arthur Baking. Ingredient Weight Chart (all-purpose flour 120 g per cup). https://www.kingarthurbaking.com/learn/ingredient-weight-chart
What can make this go out of date
- none at runtime
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