To scale a recipe, multiply every ingredient by a conversion factor — the servings you want divided by the servings the recipe makes.
Scaling a recipe up or down comes down to one number: the conversion factor, which is the servings you want divided by the servings the recipe makes. Want 6 portions from a recipe that serves 4? The factor is 1.5, and you multiply every ingredient by it. That works cleanly for most things — and falls apart for a few that do not scale in a straight line, which is where halved cakes come out flat and doubled curries come out over-spiced. This guide covers the method, the ingredients that break the rule, and how to handle pan sizes and cooking times, so a scaled recipe actually works. The CalcRange Recipe Scaler Calculator does the multiplication for every ingredient at once.
The Conversion Factor
Conversion factor = servings you want ÷ servings the recipe makes
Then: new amount = original amount × conversion factor
A factor above 1 scales up, below 1 scales down. Doubling is a factor of 2, halving is 0.5, and going from 4 servings to 10 is a factor of 2.5. Once you have the factor, every ingredient uses the same one, which is what keeps the proportions of the dish intact.
Worked Example
A recipe serves 4. You want 6. Factor = 6 ÷ 4 = 1.5.
| Ingredient | Original | × 1.5 |
|---|---|---|
| Flour | 200 g | 300 g |
| Sugar | 150 g | 225 g |
| Eggs | 2 | 3 |
| Milk | 100 ml | 150 ml |
| Butter | 80 g | 120 g |
Notice the eggs. Two times 1.5 is three, which happens to be whole, but scaling often lands you on 2.5 or 4.5 eggs. When it does, round to a whole egg and nudge the liquid slightly, since you cannot easily use half an egg without beating one and measuring it out.
Scale Your Recipe
Enter the original servings, your target servings, and the ingredients into the CalcRange Recipe Scaler Calculator and it applies the factor to everything at once. For switching between cups, grams, and millilitres, the unit converter handles the measurements.
What Doesn’t Scale Linearly
The conversion factor treats every ingredient as if doubling it doubles its effect. For most that is true. For a handful it is not, and these are where scaled recipes go wrong.
Salt, spices, and strong flavourings. These often need less than the factor suggests. Doubling a curry rarely needs double the chilli, because perception of heat and seasoning is not linear. Scale them at first by around three-quarters of the factor, taste, and adjust up. It is easy to add more and impossible to remove.
Leavening agents. Baking powder and baking soda do not scale cleanly in large jumps, especially when you change the pan and therefore the depth of the batter. Doubling a cake often needs slightly less than double the raising agent to avoid it rising too fast and collapsing.
Alcohol, and anything that cooks off. Liquids that evaporate during cooking do not scale in proportion to a larger, deeper pot where less surface is exposed. A doubled braise may end up wetter than expected.
Yeast in bread is another that resists simple doubling, since fermentation depends on time and temperature as much as quantity.
Pan Size and Cooking Time
This is the step most people forget, and it ruins more scaled bakes than the ingredients do.
Doubling a cake batter and pouring it into the same tin gives you a much deeper cake that cooks completely differently: the outside sets long before the middle. You need a larger tin, or two tins, so the batter depth stays similar to the original.
Cooking time does not scale with the factor either. A cake with twice the batter in an appropriately larger tin does not take twice as long — it takes somewhat longer, but the depth matters more than the total volume. The reliable approach is to keep the original temperature, judge doneness by the usual tests rather than the clock, and start checking before you expect it to be ready. For stovetop dishes, a bigger pot may need a little longer to come up to heat, but the per-portion cooking time barely changes.
Scaling and Unit Conversion
Scaling and converting units are separate jobs, and doing both at once is where arithmetic errors creep in. Scale first in the recipe’s own units, then convert if you need to.
A rough guide for common baking ingredients, since cup measures vary: one cup of flour is roughly 120 to 125 g, one cup of granulated sugar about 200 g, and one cup of liquid about 240 ml. These are approximate, because a cup measures volume while a scale measures weight, and a packed cup of flour weighs noticeably more than a sifted one. For baking, where ratios matter, weighing in grams is more reliable than cups, and our metric and imperial conversion guide covers the method.
Common Mistakes
- Scaling salt and spices by the full factor, which over-seasons larger batches.
- Doubling batter into the same tin, giving a cake that burns outside and stays raw inside.
- Assuming cooking time scales with quantity; depth matters more than total volume.
- Trying to use fractional eggs precisely instead of rounding and adjusting the liquid.
- Converting units and scaling in the same step, which invites mistakes. Do one, then the other.
- Scaling leavening agents by the full factor in large jumps, which can make a bake rise and collapse.
Frequently Asked Questions
How do I scale a recipe up or down?
Divide the servings you want by the servings the recipe makes to get a conversion factor, then multiply every ingredient by it. Going from 4 to 6 servings is a factor of 1.5. Scale salt and spices more cautiously than the factor suggests, and adjust the pan size to match.
Why can’t I just double everything?
Most ingredients double fine, but salt, spices, leavening agents, and evaporating liquids do not scale in a straight line. Doubling a curry rarely needs double the chilli, and doubling a cake needs a larger tin and slightly less than double the raising agent. Straight doubling of these is what spoils scaled dishes.
How do I handle half an egg?
Round to a whole number and adjust the liquid slightly to compensate. If you need precision, beat one egg and measure out half by volume, since a large egg is roughly 50 ml beaten. For most recipes, rounding and a small liquid tweak is enough.
Does cooking time change when I scale a recipe?
Yes, but not in proportion to the quantity. What matters is depth, not total volume. A doubled cake in a larger tin takes somewhat longer, not twice as long, so keep the temperature the same and judge doneness by testing rather than the clock, checking early.
Do I need a bigger pan when I scale up?
For baking, almost always. Pouring doubled batter into the original tin makes it too deep, so the outside sets before the middle cooks. Use a larger tin or split between two, aiming to keep the batter depth close to the original recipe.
Should I scale in cups or grams?
Grams, especially for baking. A cup measures volume and can hold noticeably different weights depending on how the ingredient is packed, while a scale is consistent. Weighing keeps the ratios accurate, which matters far more in baking than in most stovetop cooking.
How do I scale a recipe to a specific pan size?
Compare the pan areas or volumes and use that ratio as your factor. For round tins, the area scales with the square of the radius, so a tin twice the diameter holds about four times as much. Match the batter quantity to the new tin’s capacity rather than to servings alone.
The Bottom Line
Scaling is one factor — target servings divided by original servings — applied to every ingredient. That handles most of the recipe, but season strong flavourings and leavening below the factor and taste as you go, and remember that a bigger batch usually needs a bigger pan and a fresh judgement on cooking time rather than a scaled clock. Scale in the recipe’s own units first, then convert. Let the recipe scaler calculator do the multiplication, and weigh in grams when you bake.
Cup-to-gram weights are approximate and vary by ingredient and how it is packed. Last reviewed: August 2026. Evergreen content — recommended editorial review: every 12 months.