Recipe Converter and Scaler

How to use this converter

1. Paste the ingredient list, one per line. Quantity first, the way recipes are written. Fractions, half symbols, ranges and section headers all survive; anything with no number in front of it is passed through untouched rather than mangled.
2. Say what you are changing. Servings if the recipe tells you what it makes, a multiplier if you just want to double it, or a pan if the recipe was written for a tin you do not own.
3. Read the flagged lines. A small handful will come back marked. Those are the ones that would have gone wrong, with the number straight multiplication would have given you shown alongside.
4. Pick your units. Leave them as written, get them back in cups and spoons you own, or convert to grams where we have a published weight for the ingredient.
5. Treat the first run as a test batch. That is the Culinary Institute of America's own advice about changing batch size, and it is the honest thing to say about any recipe you have just altered.

Why this converter is different

Every recipe converter on the first page of results does exactly one thing: it multiplies every number in your list by the same figure and rounds to the nearest eighth. That is the one operation a recipe will not tolerate, and the people who wrote those tools appear to know it. One of them concedes in its own FAQ that "cooking times and temperatures may require slight adjustments" and stops there. Another instructs you, at step twelve, to "check the converted recipe for correctness".

• It knows which ingredients not to multiply. The Culinary Institute of America publishes the rule: leaveners, thickeners, gelatin and yeast start at 75 percent of the calculated amount, and flavourings at two-thirds. Triple a cake and triple its baking powder and it rises over the sides of the pan and collapses. Quadruple a cookie recipe and the eighth-teaspoon of cloves takes over the cookie. Both of those examples are the CIA's, not ours, and no other converter implements either.
• It shows you what you would have done. A flagged line carries the naive number struck through next to the corrected one. The difference is the point, so it is on the screen rather than in a footnote.
• It converts to a measure you own. Four tablespoons comes back as a quarter cup. Five teaspoons comes back as a tablespoon plus two teaspoons. Three thirds of a cup comes back as one cup, exactly, rather than as whatever the nearest eighth happens to be.
• It solves the half-egg. Halve a three-egg recipe and every other tool prints "1.5 eggs". A large egg out of its shell weighs 50 grams, so this one tells you to use one egg and weigh 25 grams of a second beaten one, which is a thing you can actually do.
• Pans scale by area, not by the capacity on the box. Keeping the batter at the same depth is what keeps the baking time roughly the same. Scale by volume instead and you have quietly changed how long the thing needs in the oven without being told.
• You can switch the whole adjustment off. Untick one box and it behaves like every competitor. That is deliberate: a claim you can test in two seconds is worth more than one you have to trust.
• The math is tested on every build. Thirty-three sourced cases plus several thousand generated assertions: the CIA's own worked examples reproduce, every rendered measure is one a person can physically measure, no adjusted amount ever falls below what the original recipe called for, and no combination of input can produce a negative or a NaN. If any of it drifts, the site does not deploy.

How it works (the math)

One factor, applied to every line, and then a second factor applied only to the lines that need it.

factor   = desired yield / original yield
         = multiplier
         = new pan area / old pan area

scaled   = quantity x factor
adjusted = max(quantity, scaled x k)   when scaling up a sensitive ingredient

k = 0.75  leaveners, thickeners, gelatin, yeast
k = 2/3   flavourings, spices, extracts, salt

1. The recipe factor is the desired yield divided by the original yield. Forty-eight muffins from a twelve-muffin recipe is a factor of four; one loaf from a two-loaf recipe is a factor of one half. Those are the CIA's worked examples and they are both in the test suite.

2. The adjustment applies to the ingredients the CIA calls sensitive. Their published guidance is to start thickeners and leaveners at about 75 percent of the amount the factor gave you, and flavourings at about two-thirds. The reason is not arithmetic, it is physics and perception: a chemical leavener produces gas in proportion to how much of it there is, but the batter it has to lift does not get proportionally stronger, and a flavour compound four times as concentrated does not taste four times as good, it tastes like cloves.

3. The floor is the part most people would get wrong. Applied literally at a factor of 1.1, "75 percent of the calculated amount" hands you less baking powder for a bigger cake, which is absurd. So no adjusted amount is ever taken below what the original recipe asked for. That makes the reduction start to bite at a factor of about 1.33 for leaveners and 1.5 for flavourings, which is exactly where the CIA's own examples live, and it is asserted as a fixture at both boundaries.

4. Scaling down is straight multiplication, with no adjustment at all. The percentages are published for scaling up, and going down the risk runs the other way: too little leavening rather than too much. Halving a recipe is the safe direction and the tool treats it that way.

5. Pans use area. A round pan is pi times the square of its radius, everything else is length times width. An eight-inch round to a nine-inch round is a factor of 1.27, not the 1.5 you might guess from the diameters. Holding the area ratio holds the batter depth, which is what holds the baking time.

Limitation, stated plainly. Changing batch size changes more than quantities. It changes mixing time, how fast a bowl of batter warms up, how deep the pan is loaded and how long the middle takes to set. None of that is an input to anything here, and no calculator can make it one. The CIA's advice is to make a test batch when you change batch size, and that remains the right advice.

Three worked examples

Tripling a cake

A recipe with two and a half cups of flour and a tablespoon and a half of baking powder, taken to three times the size. The flour goes to seven and a half cups, straight, because flour is structural and structural ingredients scale. The baking powder does not go to four and a half teaspoons. It goes to a tablespoon plus three eighths of a teaspoon, which is 75 percent of the multiplied amount. That gap is roughly a quarter of the leavening in the recipe, and it is the difference between a cake with a dome and a cake with a crater.

Halving a recipe with three eggs

The flour halves, the sugar halves, the baking powder halves, because scaling down needs no correction. The eggs are the interesting line: one and a half of them. This gives you one egg plus 25 grams, because a large egg out of the shell is 50 grams, so you beat a second egg and weigh half of it. If you would rather do that by volume, our grams to cups converter will tell you what 25 grams of most things looks like in a spoon, though for eggs the scale is genuinely the easier route.

A recipe written for an eight-inch round, and you own a nine by thirteen

The eight-inch round is 50 square inches of floor, the nine by thirteen is 117, so the factor is 2.33 and not the "about double" most people reach for. Two and a half cups of flour becomes five and three-quarter cups. Three eggs becomes seven, not "6.98", because 49 grams of egg is an egg. The baking powder is held back again. Batter this size wants a food processor or a stand mixer rather than a bowl and a spoon, and it wants a bowl with headroom, because a tripled batter that fills its bowl to the rim cannot be folded without losing the air you just beat into it.

Frequently asked questions

Can you just double a recipe?

For most of it, yes. Flour, sugar, fat, dairy, eggs and anything structural doubles cleanly. What does not double cleanly is the short list of ingredients that work by reaction or by perception: baking powder, baking soda, yeast, cornstarch, gelatin, salt, spices and extracts. The Culinary Institute of America's guidance is to start those at 75 percent of the doubled amount for the leaveners and thickeners, and two-thirds for the flavourings, then taste or test. Doubling is the gentlest case, though; the trouble really starts at three and four times, where a straight multiplication of the baking powder will visibly ruin a cake.

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

Beat one egg, weigh out half of it, and use that plus one whole egg. A US large egg out of the shell is 50 grams by USDA measurement, so half an egg is 25 grams. The white is 33 grams of that and the yolk 17, which matters if the recipe separates them: half of three yolks is one yolk plus 9 grams, not "one and a half yolks". Rounding to two whole eggs adds about 17 percent more egg to the batch, which in a custard or a cake batter is enough to feel.

What is the recipe conversion factor?

The desired yield divided by the original yield. If a recipe makes 12 muffins and you want 48, the factor is 4. If it makes two loaves and you want one, the factor is 0.5. Multiply each ingredient by that number, then convert the results to sensible measures and hold back the sensitive ones. That sequence is the standard professional method and it is what this page automates.

How do I convert a recipe to a different pan size?

Compare the pans by area, not volume. Work out the floor area of each (pi times radius squared for a round pan, length times width for a rectangular one) and divide the new by the old. An eight-inch round is 50 square inches, a nine-inch is 64, a nine by thirteen is 117. The reason area beats volume is that it keeps the batter at the same depth, and depth is what determines how long heat takes to reach the middle. Scale by volume and the cake is deeper and needs longer, and nothing will have told you so. One caveat: this works for flat-bottomed pans. Bundt and tube pans are a different shape and are better matched by their stated capacity.

Do you scale salt and spices when you double a recipe?

Not fully, and this is the one people argue about. The CIA lists seasonings among the sensitive ingredients and suggests about two-thirds of the calculated amount when scaling up, then tasting. The exception worth knowing is bread: salt in a dough is a percentage of the flour weight, it controls fermentation rather than just flavour, and it should scale with the flour exactly. If you are doubling a bread dough, scale the salt straight and only hold back the yeast.

Related tools

• Grams to Cups Converter — the sourced cup weights this page uses for its gram output, for 122 ingredients, one at a time.
• Egg Boiling Timer — the boil time for the egg you actually have, adjusted for size and elevation.
• Rice to Water Ratio Calculator — scaling rice is its own problem, because the water does not scale with the grain.
• Browse all free kitchen tools by Nora →

What actually makes a scaled recipe work

Scaling multiplies your measuring errors along with your ingredients. A cup of flour that was eight grams heavy than intended is eight grams; the same cup quadrupled is thirty-two, which is a quarter cup of flour you did not mean to add. Three things do most of the work.

• A scale, which ends the argument. Weight scales perfectly and does not care how you scoop. This is the single highest-value object in a kitchen that cooks the same thing twice, and it costs less than a bag of good flour.
• A bowl with headroom. The most common reason a doubled batter comes out dense is that it was folded in a bowl it barely fit, so half the air went out of it on the way. A five-quart bowl for a batch that would have fitted a two-quart one is not overkill.
• Odd-size measuring spoons. Halved recipes land on eighths and thirds of a teaspoon constantly. If your set stops at a quarter teaspoon, you are rounding every small ingredient in the recipe in the same direction.
• A processor for the big-batch doughs. Pastry and biscuit dough at triple scale is a race against warm butter that hands cannot win. Our best food processors guide covers which bowls handle a large, dry batch without turning it to paste, and our rice cooker guide is the equivalent for the grain side, where the machine's capacity is the real ceiling on how far you can scale.

Sources & methodology

• The Culinary Institute of America — Scaling Baking Recipes Up and Down — the recipe factor, the 75 percent figure for thickeners and leaveners, the two-thirds figure for flavourings, and the instruction to convert results to a more logical unit of measure. This is the page the whole tool is built on.
• USDA FoodData Central — egg weights out of the shell (SR Legacy 171287 whole, 172183 white, 172184 yolk): large 50 g, white 33 g, yolk 17 g, plus medium 44 g, extra-large 56 g and jumbo 63 g.
• King Arthur Baking — Ingredient Weight Chart — the measured cup weights behind the gram output, carried over from our grams to cups converter so the two tools cannot disagree.

Quantities are multiplied by the recipe factor, then leaveners, thickeners, gelatin and yeast are started at 75 percent of that amount and flavourings and seasonings at two-thirds, following the Culinary Institute of America. No adjusted amount is ever taken below the original recipe's quantity, and scaling down is straight multiplication. Volumes are re-expressed in the largest measure that lands on a real cup or spoon, to the nearest eighth of a teaspoon under a cup and the nearest quarter cup above four. Gram output uses King Arthur and USDA cup weights, and any ingredient with no published weight stays a volume rather than being estimated. Pan scaling uses floor area, pi r squared for round pans and length times width for the rest. A fixture suite asserts 33 sourced cases, the CIA's two worked examples, both adjustment boundaries, every pan pair round-tripping, 800 rendered volumes being physically measurable, and 1,056 input combinations for finiteness on every build. Reviewed by Nora Whitfield, CIA Culinary Arts, ServSafe Certified. About Nora · Last reviewed September 8, 2026.

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Free for recipe blogs, baking schools, cooking classes and anyone who publishes recipes that readers will want to halve or double. Required attribution is baked into the snippet: no fee, no account, no analytics attached to the embed.

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