What next?
Scaling a recipe changes weights, volumes and sometimes the temperature.
How to use this calculator
- Paste your ingredients, one per line with amounts.
- Set the original and desired servings.
- Read every quantity rescaled automatically.
What your result means
Each amount is multiplied by the scale factor (desired ÷ original servings), so proportions stay true. Round sensibly for whole eggs and pinches, and remember cooking times and pan sizes don’t scale in a straight line.
Why this one is different
Ingredient lines are parsed rather than retyped: quantity, unit and name are separated, multiplied by one factor and printed back in your order and your units, fractions included. That factor is stated on its own, so an oven temperature or a tin size that must not be scaled is easy to leave alone.
Scale any recipe up or down
To resize a recipe you multiply every ingredient by the same factor — the desired number of servings divided by the original. Doubling a four-person meal to eight means a factor of two; scaling it down to three means a factor of 0.75.
Paste your ingredient list with quantities at the start of each line and this reads the number, scales it, and keeps the unit and name intact. Common fractions like ½ and ¾ are recognised and returned in the same friendly form.
Formula
Each ingredient quantity is multiplied by this factor.
Example calculation
Scaling a 4-serving recipe up to 6 servings:
200 g flour × 1.5 = 300 g
every ingredient scales the same way
Frequently asked questions
Does it handle fractions?＋
Yes. It reads fractions like 1/2 or mixed numbers like 1 1/2, scales them, and shows quarters and thirds as ¼, ½, ¾, ⅓ and ⅔ where possible.
Should I scale cooking times too?＋
No — cooking time does not scale linearly. A double batch usually needs a little longer but not twice as long, and pan size matters more than quantity. Adjust by eye and use a thermometer.
Which ingredients do not scale linearly?＋
Salt, spices, leavening agents and alcohol. Doubling a cake recipe rarely means doubling the baking powder, and strong spices are better scaled by about 1.5 times when doubling, then tasted.
How do I scale to a tin of a different size?＋
Compare areas rather than diameters. A 23 cm round tin has about 40 percent more area than a 20 cm one, so that is the multiplier for the batter, not the ratio of the diameters.
Should I scale by weight or volume?＋
Weight, wherever a recipe gives it. Cup measures of flour vary by up to 20 percent depending on how they are filled, which is what ruins scaled baking recipes.
Do cooking times change when I scale up?＋
Usually, but not proportionally. A double batch in a wider tin cooks in a similar time; the same batter in a deeper tin needs longer at a slightly lower temperature. Judge doneness, not the clock.
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Assumptions & limitations
Scaling ingredients is arithmetic; scaling cooking is not.
- Quantities scale linearly, but cooking times do not. A doubled cake takes considerably longer than twice as long in the middle and can burn at the edges — increase time, not temperature.
- Leavening agents, salt and strong spices often need less than a straight multiple when scaling up, and can disappear entirely when scaling down.
- Pan size matters as much as quantity. Doubling a recipe into the same tin changes the depth and therefore the bake.
- Volume-to-weight conversions depend on the ingredient — a cup of flour and a cup of sugar weigh very different amounts — so scale within the same unit system where you can.
Sources & references
Ingredient measures and cooking conversion conventions follow:
- BBC Good Food — weight, volume and oven temperature conversion guides
- USDA FoodData Central — per-100 g composition and portion weights for individual ingredients
What scales linearly and what does not
Most ingredients scale straight: flour, sugar, liquid, meat, vegetables. Three things routinely do not. Salt and strong spices scale sub-linearly — doubling a recipe rarely wants double the chilli, and tasting as you go beats the arithmetic. Raising agents behave similarly, because bicarbonate and baking powder react with a fixed amount of acid and moisture; heavy-handed scaling gives a metallic taste and a collapsed crumb. And anything that cooks by surface area rather than mass, such as a roux or a reduction, needs its own judgement rather than a multiplier.
Pan size and cooking time are the real constraints
Doubling a cake batter does not mean doubling the tin depth — a deeper cake cooks more slowly at the edges and can be raw in the middle when the outside is done. The usual answer is to keep the depth and increase the area: two tins rather than one deeper one. Cooking time scales with thickness, roughly as its square, not with total mass, so a joint twice the weight but the same thickness takes only slightly longer, while one twice as thick takes far longer. Scale the ingredients here, then set the time by the thermometer rather than by the multiplier.