To scale a recipe, convert every ingredient to grams, find your scaling factor (the new yield divided by the original yield), and multiply each weight by that factor. Making 1.5 times a recipe that calls for 2 cups of all purpose flour means 240 g × 1.5 = 360 g. That's how to scale a recipe without trying to measure 3/8 cup or a third of an egg by eye.
| Ingredient | Original (grams) | Half (× 0.5) | One and a half (× 1.5) | Double (× 2) |
|---|---|---|---|---|
| All purpose flour, 2 cups | 240 g | 120 g | 360 g | 480 g |
| Granulated sugar, 1 cup | 198 g | 99 g | 297 g | 396 g |
| Brown sugar, packed, 1/2 cup | 106.5 g | 53.3 g | 159.8 g | 213 g |
| Butter, 1/2 cup | 113 g | 56.5 g | 169.5 g | 226 g |
| Milk, 1 cup | 227 g | 113.5 g | 340.5 g | 454 g |
| Large eggs, 2 | 100 g | 50 g | 150 g | 200 g |
Why weight makes scaling so much easier
Cups and spoons were never designed to be multiplied. Scale 3/4 cup by 1.5 and you get 1 1/8 cups, which no measuring set has. Halve 1/3 cup and you're stuck with 1/6 cup. Every awkward fraction is a chance to guess.
Grams don't have that problem. Multiply 198 by 1.5 and you get 297. You pour until the scale says 297, and you're done. The math is the same for every ingredient, whether it's flour, sugar or milk.
Finding your scaling factor
The factor is just new amount ÷ original amount. You can base it on whatever matters for your bake:
- Servings: a recipe for 12 that you want to make for 18 has a factor of 18 ÷ 12 = 1.5.
- Batch size: half a batch is 0.5, a double batch is 2.
- Pan size: compare pan areas. An 8 inch square pan is 64 square inches and a 9 by 13 inch pan is 117, so moving from the small pan to the big one is a factor of about 1.83.
Round pans work the same way. A 9 inch round has an area of about 63.6 square inches (3.14 × 4.5 × 4.5), so it holds roughly the same batter as an 8 inch square.
How to scale a recipe step by step
- Convert the original recipe to grams using one chart, such as King Arthur Baking's.
- Work out your scaling factor.
- Multiply every ingredient by the factor, including salt, leavening and flavorings.
- Round sensibly: whole grams for big amounts, one decimal place for small ones.
- Write the new recipe down before you start, so you're not doing math with buttery hands.
- Choose a pan that fits the new amount, and check for doneness early, since baking time doesn't simply multiply along with the ingredients.
Ingredients that need a little extra care
- Eggs. King Arthur Baking counts a large egg as 50 g without the shell. For half an egg, beat one egg and weigh out 25 g.
- Salt, yeast and leavening. These amounts are small, so rounding errors matter more. Keep a decimal place.
- Bake time and temperature. Don't multiply them. A deeper or wider pan changes how heat moves through the batter, so watch the bake rather than the clock.
- Spices and extracts. Scale them first, then taste and adjust if you can.
For tips on the tiny amounts, see our guide to measuring small ingredients without guessing.
A practical tip: when you halve a recipe that calls for 1/2 tsp of baking soda, you need a quarter teaspoon's worth. King Arthur Baking puts 1/2 tsp at 3 g, so that's 1.5 g, an amount that's easy to get wrong. The MeasureMate digital measuring spoon scoops and weighs in one step and reads in 0.1 g steps, so small scaled amounts come out right. Use the tare button to zero it between ingredients.
Quick questions
Can I just double the baking time when I double a recipe?
No. Bake time depends on the pan and the depth of the batter, not the total amount. Start checking at the original time and keep going until it's done.
How do I use half an egg?
Beat one large egg and weigh out half. With King Arthur Baking's 50 g egg, that's 25 g.
Do I scale salt and leavening too?
Yes, scale them by the same factor as everything else, and weigh them rather than eyeballing a fraction of a spoon.
Weights based on the King Arthur Baking ingredient weight chart.