Use the How to Scale A Recipe Up or Down
To scale a recipe, divide the number of servings you want by the number of servings the recipe currently makes. That gives you the scale factor. Multiply each ingredient amount by that scale factor.
Scale factor = desired servings ÷ original servings. New ingredient amount = original ingredient amount × scale factor. For example, changing 4 servings to 10 servings gives a scale factor of 2.5.
Want the ingredients scaled for you?
Use the recipe scaler to change servings, add ingredient rows and choose exact, kitchen-friendly or fraction rounding.
Step 1: find the scale factor
The scale factor tells you how much bigger or smaller the recipe needs to become. It works whether you are doubling a recipe, halving it, cooking for one person, or batch cooking for a group.
Scale factor = desired servings ÷ original servings
Example:
Original recipe = 4 servings
Desired recipe = 6 servings
Scale factor = 6 ÷ 4 = 1.5A scale factor above 1 makes the recipe bigger. A scale factor below 1 makes it smaller. A scale factor of 1 means the recipe stays the same size.
Step 2: multiply each ingredient
Once you know the scale factor, multiply every ingredient quantity by it. This is easiest for grams, kilograms, millilitres and litres because they scale cleanly.
| Original ingredient | Scale factor | New amount |
|---|---|---|
| 200g flour | 1.5 | 300g flour |
| 100g sugar | 1.5 | 150g sugar |
| 250ml milk | 1.5 | 375ml milk |
| 2 tbsp oil | 1.5 | 3 tbsp oil |
Worked recipe scaling examples
Double a recipe
Going from 4 servings to 8 servings gives a scale factor of 2. Multiply every ingredient by 2. So 300g pasta becomes 600g pasta.
Halve a recipe
Going from 4 servings to 2 servings gives a scale factor of 0.5. Multiply every ingredient by 0.5. So 200ml cream becomes 100ml cream.
Scale 6 servings to 10
10 ÷ 6 = 1.67. A 300g ingredient becomes about 500g after rounding. This is where kitchen-friendly rounding helps.
Scale one portion to four
Going from 1 serving to 4 servings gives a scale factor of 4. This is simple for weighed ingredients but may need judgement for seasoning.
How to round scaled ingredients
Exact maths can produce awkward kitchen amounts. A calculator might return 83.33g, 1.67 eggs or 0.38 teaspoons. The right answer depends on the ingredient and how precise the recipe needs to be.
- For flour, sugar, rice and pasta, rounding to the nearest gram or 5g is usually practical.
- For liquids, rounding to the nearest 5ml or 10ml is often easier to measure.
- For spices, salt and raising agents, small changes can affect flavour or texture.
- For eggs, round carefully or use beaten egg by weight when precision matters.
For everyday cooking, rounded amounts are usually fine. For baking, preserving or recipes that rely on chemical reactions, exact measurements matter more.
Ingredients you should not scale blindly
Most main ingredients scale cleanly. Some ingredients need judgement because flavour, texture and cooking behaviour do not always grow in a perfect straight line.
| Ingredient type | Why it can be tricky | Practical approach |
|---|---|---|
| Salt | Can become overpowering quickly | Scale partly, then taste and adjust |
| Chilli and strong spices | Heat and flavour can intensify | Start lower, add more if needed |
| Baking powder and yeast | Affects rise, texture and timing | Use recipe-specific judgement |
| Eggs | Can create awkward fractions | Round or weigh beaten egg |
| Cooking time | Does not double just because the recipe doubles | Check doneness, pan size and depth |
Scaling cups, grams and spoon measurements
Scaling grams and millilitres is straightforward. Scaling cups to grams is more complicated because a cup is a volume measurement, while grams measure weight. A cup of flour does not weigh the same as a cup of sugar, oil or milk.
For recipes that use cups, first decide whether you want to keep the result in cups or convert to grams. For baking, weighing ingredients is usually more consistent than relying on how tightly a cup is packed.
Need to convert cups, spoons or grams?
The cooking unit converter can convert between teaspoons, tablespoons, cups, ml, litres, grams, kilograms, ounces and pounds.
Servings, portions and recipe yield
A serving is the amount the recipe says it makes. A portion is the amount someone actually eats. These can be different, especially for children, packed lunches, batch cooking or side dishes.
Recipe yield means the total amount a recipe produces. Before scaling, check whether the original recipe is measured by servings, pieces, portions, trays, jars or total weight.
Scaling recipes for cost per serving
Scaling a recipe can also help you estimate shopping costs. Once you know the new ingredient amounts, you can work out the total grocery cost and divide it by the number of servings.
Cost per serving = total recipe cost ÷ number of servings
Example:
Recipe cost = £12
Servings = 6
Cost per serving = £12 ÷ 6 = £2This is useful for batch cooking, meal prep, family meals and comparing homemade meals with shop-bought alternatives.
Common mistakes when scaling recipes
- Changing the number of servings but forgetting to scale every ingredient.
- Adding discounts, portions or costs together without checking the unit.
- Doubling seasoning too aggressively before tasting.
- Assuming cooking time doubles when the recipe doubles.
- Using cups-to-grams conversions without selecting the ingredient.
- Ignoring pan size, tray depth or oven space when scaling up.
FAQs
How do I scale a recipe?
Divide the number of servings you want by the number of servings the recipe currently makes. That gives you the scale factor. Then multiply each ingredient quantity by that scale factor and round the result into a practical kitchen amount.
How do I double a recipe?
To double a recipe, use a scale factor of 2. Multiply every ingredient amount by 2. For example, 250g flour becomes 500g flour, 1 tablespoon oil becomes 2 tablespoons, and 4 servings become 8 servings.
How do I halve a recipe?
To halve a recipe, use a scale factor of 0.5. Multiply each ingredient by 0.5. For awkward ingredients such as one egg, you can round carefully or beat the egg and use roughly half by weight or volume.
Can all ingredients be scaled exactly?
No. Most main ingredients can be scaled mathematically, but salt, spices, yeast, baking powder, eggs and cooking time may need judgement. For everyday cooking, taste and adjust. For baking, follow the recipe more carefully.
Does cooking time double if I double a recipe?
Usually not. Cooking time depends on pan size, food depth, oven temperature and how heat moves through the dish. A larger batch may take longer, but it normally needs checking by texture, temperature or doneness rather than a simple multiplier.
Is it better to scale recipes in grams or cups?
Grams are usually more consistent because they measure weight. Cups measure volume, so the weight depends on the ingredient and how it is packed. For baking, grams are normally easier to scale accurately.
Sources and notes
This guide uses stable kitchen maths formulas and does not rely on time-sensitive rates or statistics. Recipe results are practical estimates, and ingredient behaviour can vary by brand, density, pan size and cooking method.