How to Scale a Recipe

Multiply the ingredients, then think again about four things: eggs, seasoning, the tin or pan, and the cooking time. Those are the four that do not simply follow the multiplier.

To scale the ingredient list itself: Recipe Serving Scaler

Flour, sugar, butter, milk, water, meat, vegetables and stock all scale straight up and down. Anything you weigh or pour is usually safe to multiply.

Eggs. They come in whole units. A recipe with three eggs multiplied by 1.5 wants four and a half. Beat the extra egg and weigh half of it, about 25 g of beaten egg is half a medium egg, or nudge the whole recipe to a multiplier that lands on whole eggs.

Salt, spices and strong flavours. These scale by less than the multiplier. Doubling chilli, garlic or salt in a stew often overshoots. Add roughly one and a half times as much and taste.

Raising agents. Baking powder and bicarbonate of soda do scale, but errors multiply too, a heavy hand at triple quantity tastes soapy. Measure them properly rather than by eye.

Yeast. A larger dough ferments faster because it holds its own heat. Scale the yeast and then watch the dough, not the clock.

Liquid in anything that simmers. A wider pan evaporates faster and a deeper one slower, so a doubled sauce may need less than double the liquid.

Cooking time. Depth drives baking time far more than total quantity. Twice the batter in twice the tins takes almost the same time; twice the batter in one tin takes considerably longer.

Cakes are the least forgiving thing to scale, because the tin changes how the heat gets in. Match the tin's area rather than its width, work out the batter quantity for the new tin, and expect the time to move.

Cake Tin Converter handles the area arithmetic, Cake Batter Quantity gives the amount for the new tin, and Traybake Converter deals with rectangular tins. The full explanation is in the cake tin guide's calculator, with the reasoning set out in the related guide below.

Doughs are the easiest thing to scale reliably, because bakers already write them as percentages of the flour weight. Set the flour weight you want and every other ingredient follows.

For a formula you can scale to any batch size: Baker's Percentage Calculator

Scaling the pan but not the heat. A crowded pan steams instead of browning. Use two pans or cook in batches.

Doubling salt without tasting. Season at the end, at the new quantity.

Keeping the original cooking time. Check early and often; the recipe's time belonged to the recipe's quantity.

Converting cups then scaling. Do it in grams first, rounding errors multiply along with everything else: Cups to Grams.