Recipe scaling calculator

The formula

$$k = \frac{s_2}{s_1}$$ $$\text{new amount} = k \times \text{old amount}$$

$s_1$ is the number of servings the recipe makes, $s_2$ the number you want and $k$ the scale factor.

Where it comes from

A recipe is a set of proportions. If 250 g of flour serves 4, each serving takes $250/4 = 62.5$ g. For 6 servings you need $6 \times 62.5 = 375$ g. Doing that for every ingredient is the same as multiplying each one by $6/4 = 1.5$.

That single factor keeps every ratio in the recipe the same, which is what keeps it tasting the same.

Worked example

A pancake recipe for 4, scaled to 6, so $k = 1.5$:

Ingredient	For 4	For 6
Flour	250 g	375 g
Milk	300 mL	450 mL
Eggs	2	3
Butter	2 tbsp	3 tbsp

What doesn’t scale linearly

• Eggs. Round to whole eggs, or beat one and use part of it.
• Baking time. A bigger cake in a deeper pan takes longer, but not 1.5 times longer. Check early and often.
• Pan size. Doubling a recipe in the same pan makes it twice as deep. Use a pan with about $k$ times the area.
• Salt, spices and leavening. These can taste stronger in very large batches. Scale them and adjust to taste.
• Evaporation. Sauces in a wider pot reduce faster.

Last checked November 11, 2026