The formula
Scale factor = servings needed ÷ servings the recipe makes. Multiply every ingredient quantity by that factor. Scaling a 4-serving recipe to 6 gives a factor of 1.5, so 2 cups of stock becomes 3 cups.
Worked examples
| Recipe serves | You need | Factor | 1 cup becomes |
|---|---|---|---|
| 4 | 6 | 1.5 | 1.5 cups |
| 8 | 2 | 0.25 | 0.25 cups |
| 6 | 6 | 1 | 1 cup |
What does not scale
Salt, chilli and leavening rarely scale in a straight line — doubling a recipe and doubling the salt often oversalts it, so season and taste instead. Pan size and cooking time also change: a doubled batter in the same tin needs longer, and a batch baked in a much deeper tin may brown outside before it cooks through.
Cups, grams and the awkward fractions
A factor like 1.5 turns neat cups into awkward ones. When the scaled amount is hard to measure, convert it to grams with the Cups to Grams Converter and weigh it, which is both more accurate and easier at odd quantities.
Related guides
Frequently asked questions
Can I scale a recipe down?
Yes. Asking for fewer servings than the recipe makes gives a factor below 1 and shrinks every quantity.
Should I scale the cooking time too?
Not by the same factor. Time depends on thickness and pan size, so start checking early rather than multiplying the minutes.
What about eggs?
The calculator gives the exact fraction. For small batches it is usually better to weigh a beaten egg than to guess at half an egg by eye.