Scale any recipe to the servings you actually need.
Change the servings — or set a direct factor like halve or double — and every
ingredient is multiplied by the right number. Quantities accept fractions like
1 1/2 and 3/4, and the scaled results come back as friendly
cooking fractions you can actually measure, with the exact decimal shown alongside.
Servings or direct factor·Fraction-aware·Add & remove ingredients
Read this first
Scaling is pure multiplication for ingredient amounts — and only for amounts.
Cook time, pan size, and leavening do not scale by the same factor, so treat those as
judgment calls, not math. Seasonings often need less than a straight multiply when you
scale up, so taste as you go. And eggs are discrete: a half egg means beating one and
using half. The numbers here are a reliable starting point, not a guarantee of a perfect
result.
Choose how you want to scale — by servings, or by a direct multiply factor — then enter your ingredients below. Quantities can be whole numbers, decimals, or fractions like 1/2 or 1 1/2.
What the recipe makes as written.
What you want to make.
0.5 to halve, 2 to double, 3 to triple, and so on.
QuantityUnitIngredientScaled
The math, honestly
How the scaling is figured
It's one multiplication, repeated. First the tool finds a scale factor.
By servings, that's desired ÷ original — going from 4 servings
to 6 gives 6 ÷ 4 = 1.5. By direct factor, you set it yourself
(0.5 to halve, 2 to double).
Then every ingredient's scaled amount is quantity × factor.
So 2 cups of flour at 1.5× becomes 3;
1 tsp salt becomes 1 1/2; 1/2 cup sugar becomes
3/4. Fractions you type in — 1 1/2, 3/4 —
are parsed to decimals first, multiplied, then turned back into the nearest clean cooking
fraction.
What is not multiplied: cook time, oven temperature, pan size, and to a
degree leavening and seasoning. A doubled cake does not bake in double the time, and a
bigger pan is not a bigger number times the linear size — it scales by area. Those
stay judgment calls; the tool deliberately won't pretend they're arithmetic.
The cooking fractions it rounds to
A scaled amount is rarely a tidy fraction on its own — 0.7 cups isn't something you
can scoop. So within each whole number, the tool snaps the leftover to the nearest of these
practical fractions, the ones marked on measuring cups and spoons. The exact decimal is
always shown in parentheses so nothing is hidden.
Fraction
Decimalapproximate
Rounds from a result near
0
0.00
nothing left over
1/8
0.125
about 0.06 to 0.19
1/4
0.25
about 0.19 to 0.29
1/3
0.333
about 0.29 to 0.42
1/2
0.50
about 0.42 to 0.58
2/3
0.667
about 0.58 to 0.71
3/4
0.75
about 0.71 to 0.81
7/8
0.875
about 0.81 to 0.94
A leftover above about 0.94 rounds up to the next whole number (so 1.96 cups shows as 2,
not 1 and 7/8 plus a sliver). For precise baking, weigh in grams and use the exact decimal
rather than the fraction.
Scaling well, not just scaling
The arithmetic is the easy part. These four things are where scaled recipes go wrong, and
none of them is a straight multiply.
Cook time and temperature don't double
Heat reaches food through its surface, so doubling the batter does not double the bake. Keep the oven temperature the same and start checking around the original time, then go by doneness cues — internal temperature, color, a clean toothpick — not the clock. A deeper or wider batch may need a little longer, but never twice as long.
Pan size scales by area, not by length
An 8-inch round pan holds noticeably less than a 9-inch one, but not in the 8-to-9 ratio you'd guess. Area goes with the square of the radius, so the real jump is closer to 1.3×. For sheet and rectangular pans, compare length × width. Match your batter volume to the pan's area or you'll get a too-thin layer that overbakes or a too-deep one that sinks.
Season and leaven by taste, not by factor
Salt, spices, and other seasonings rarely need the full multiplied amount when you scale up — flavors concentrate differently in a larger batch. Add most of the scaled amount, taste, and adjust. Baking powder and baking soda are chemically active; multiplying them several times over for a big batch can throw off rise and texture. When in doubt, find a recipe written at the larger size.
Eggs and other discrete items don't divide cleanly
When the math hands you 1 1/2 eggs, you can't crack half an egg neatly — beat a whole egg and measure out the fraction (a large egg is about 3 tablespoons, so half is roughly 1 1/2 tablespoons), or round to the nearest whole and adjust. The same goes for whole items like a single onion or one can of beans: round sensibly rather than chasing the decimal.
Where to buy
Got your numbers? Here's where to pick up what you need:
The handful of terms behind the scaler, in plain English. These are background definitions
for resizing a recipe, not a substitute for a tested recipe at the size you need.
Scale factor
The single number every ingredient is multiplied by. By servings it's desired ÷ original; set directly it's whatever you choose. A factor above 1 scales up, below 1 scales down, and exactly 1 leaves the recipe unchanged.
Servings (yield)
How many portions a recipe makes as written. Scaling by servings just compares the yield you want to the yield you have. If a recipe doesn't state its yield, estimate it, or switch to the direct factor instead.
Mixed number
A whole number plus a fraction, like 1 1/2 or 2 3/4. The scaler reads these on input (type them with a space between the whole and the fraction) and produces them on output, because that's how cooks actually read a measuring cup.
Friendly rounding
Snapping an awkward decimal to the nearest measurable fraction — the set 0, 1/8, 1/4, 1/3, 1/2, 2/3, 3/4, 7/8. It trades a little precision for something you can scoop. The exact value stays visible in parentheses for anyone who'd rather weigh.
Discrete ingredient
An ingredient that comes in whole units you can't easily split — eggs, cans, whole onions. Scaling can hand you a fraction of one; the practical fix is to measure the fraction by volume or round to a whole and adjust, not to take the decimal literally.
Weighing (grams)
Measuring ingredients by mass on a kitchen scale rather than by volume. It sidesteps fraction rounding entirely and is the most accurate way to scale baking, where a little too much flour changes the result. For weight-based scaling, use the exact decimal the tool shows, not the rounded fraction.
Frequently asked
Multiply every ingredient amount by 2. A recipe calling for 1 cup of flour needs 2 cups; 1/2 teaspoon of salt becomes 1 teaspoon. In the scaler, either set original servings to the recipe's yield and desired servings to twice that, or just type 2 into the direct factor box. The one thing not to double is the cook time — and taste before doubling strong seasonings outright.
Multiply everything by 0.5. So 1 cup becomes 1/2 cup, 1 1/2 teaspoons becomes 3/4 teaspoon, and 3 eggs becomes 1 1/2 eggs. Set desired servings to half the original, or type 0.5 into the direct factor box. For eggs and other discrete items, beat one egg and use half, or round to the nearest whole and adjust. Use a smaller pan, and start checking for doneness earlier than the original time.
No. Cook time does not scale with the amount of food. Doubling a cake batter does not mean doubling the bake time. Heat reaches food through its surface, and a larger or deeper batch changes how quickly that happens — but not in a simple multiply-by-two way. Keep the oven temperature the same, start checking around the original time, and rely on doneness cues (internal temperature, color, a toothpick test) rather than the clock.
Divide the servings you want by the servings the recipe makes to get a scale factor, then multiply every ingredient by it. To take a 4-serving recipe to 6 servings, the factor is 6 ÷ 4 = 1.5, so a 2-cup ingredient becomes 3 cups and a 1-teaspoon ingredient becomes 1 1/2 teaspoons. The scaler does this for the whole list at once and rounds results to practical cooking fractions.
Scale by pan area or volume, not by linear dimensions. A 9-inch round has roughly 64 square inches; an 8-inch round about 50 — so 8 to 9 inches is about a 1.3× increase, not 9/8. For two pans of the same depth, compare length × width. Use that area ratio as your scale factor for the batter. Depth affects bake time, so adjust the time by judgment and watch for doneness rather than assuming it scales too.
Eggs are discrete, so they rarely scale to a clean whole number. When the math gives you something like 1 1/2 eggs, crack and beat the eggs, then measure the fraction by volume: a large egg is about 3 tablespoons beaten, so half an egg is about 1 1/2 tablespoons. For small changes you can often round to the nearest whole egg, but in baking — where egg is structural — measuring the fraction is more reliable.
Use the scaled amount as a starting point, not a final answer. Seasonings like salt and spices often need less than a straight multiply when you scale up, so add most of the scaled amount, taste, and adjust. Leavening agents such as baking powder and baking soda are chemically active and don't always scale linearly in large batches; when in doubt, follow a trusted larger-batch recipe rather than multiplying a small one several times over.
The main number is rounded to a friendly cooking fraction you can actually measure, like 3/4 cup or 1 1/2 teaspoons. The decimal in parentheses is the exact, unrounded result, so you can see how much rounding happened and decide for yourself. For most cooking the rounded fraction is fine; for precise baking you may prefer to weigh ingredients in grams, in which case the decimal is the number to use.
Common mistakes
Four places where recipe scaling goes wrong that arithmetic alone cannot fix.
Scaling leavening and salt linearly
Baking powder, baking soda, and salt do not behave proportionally in large batches. Leavening is chemically active: too much in a doubled batch can cause a cake to rise rapidly and then collapse, or leave a metallic aftertaste. Salt flavour also intensifies non-linearly with concentration. The safe approach is to scale these to about 75–80% of the calculated amount, taste, and adjust — rather than trusting the multiplied number directly.
Multiplying the cook time by the same factor as the ingredients
Doubling a recipe does not double the bake time. Heat reaches food through surface area, and a larger or deeper batch changes how quickly that happens, but not in a simple proportion. Keep the oven temperature the same, start checking around the original time, and rely on doneness cues (internal temperature, colour, a clean toothpick) rather than the clock. Multiplying minutes is one of the most reliable ways to ruin a scaled recipe.
Applying a fractional egg literally
A scale factor of 1.5 applied to 3 eggs gives 4.5 eggs — you cannot crack half an egg neatly. The practical fix: crack and beat all your eggs, then measure the required fraction by volume. A large egg is about 3 tablespoons when beaten, so 0.5 egg is roughly 1½ tablespoons. For very small adjustments, rounding to the nearest whole egg is usually fine; in baking, where egg is structural, measuring the fraction is more reliable.
Not adjusting the pan size to match the scaled batter
Scaling a recipe by 1.5× and then pouring it into the original pan makes the batter deeper, which slows cooking and can leave a raw centre while the edges overbake. Pan size should scale with batter volume — which means scaling by area, not by linear dimension. A 9-inch round has roughly 63.6 in²; an 8-inch round has roughly 50.3 in². See the Baking Pan Converter for exact area comparisons.