How to scale a recipe, including salt and spices

How do you scale a recipe up or down for more or fewer people?

Work with a factor: the number of people you want, divided by the number the recipe was written for. You multiply most ingredients by that factor. Salt, spices and whole items need their own approach, and you don't calculate the pan and the cooking time. That takes five steps. The examples assume a recipe for 2 people.

Step 1: divide the new number by the old one

If the recipe is for 4 and you are cooking for 6, the factor is 6 divided by 4, so 1.5. If you are cooking for 3, the factor is 0.75.

Step 2: multiply what simply scales

Ordinary ingredients in grams or millilitres, such as vegetables, meat, pasta, milk and cream, scale proportionally. With a factor of 1.5, 600 g of potatoes becomes 900 g, and 250 ml of cream becomes 375 ml.

Step 3: count whole items as whole items

What you can count, such as eggs, onions and garlic cloves, you round to whole items, and to halves where that works. You can cut an onion in half, but not an egg. If a recipe for 2 has 2 eggs, that is 5 for 5 people. For 3 people, 1 onion becomes 1½ onions.

Step 4: go carefully with salt and spices

Don't scale salt and spices 1 to 1. In Smaquli they scale with a power of 0.85: with 2.5 times as many people, the salt goes up 2.18 times, not 2.5 times. So 1 tsp of salt becomes 2¼ tsp instead of 2½ tsp, because the app rounds to a quarter of a teaspoon. If you want to do it in your head: with twice as many people, start with about 1.8 times as much salt and taste afterwards. Scaling down is simply proportional.

Step 5: look at the pan, the time and the temperature

A factor converts quantities, not pans. Twice as much in the same pan takes longer to come to the boil, and half a portion in a big pan reduces faster. If you are going to more than twice as much or less than half, choose a different pan or split it over two pans, and keep an eye on the timings.

Why don't salt and spices simply double?

Because flavour doesn't grow in the same proportion as quantity. If you double everything, the dish is soon too salty or too sharp. At 1.5 times as many people you barely notice, but in a big pan you do: if you cook for 10 from a recipe for 2, 1 tsp of salt ends up at 4 tsp and not 5 tsp. Chilli, curry powder and dried herbs work the same way. So taste as you go, because you can always add salt but you can't take it out.

What happens to salt, eggs and a bay leaf?

Each ingredient behaves differently: eggs become whole items, a bay leaf stays one and salt grows more slowly than the rest. Choose the number of people below and see what happens to a few ingredients. The table underneath shows the same examples, for a recipe for 2 people.

Look at the salt row first. For 5 people there are 2.5 times as many eaters, but the salt becomes 2¼ tsp and not 2½ tsp. With 400 g of mince it is proportional: 400 g times 2.5 is 1000 g, and the app writes that as 1 kg.

You can see each of these kinds on the red curry ramen with dumplings recipe. Pick another number of people and see what changes.

How do you scale a baking tin or a baking dish?

Compare the area of the tins, not the width. A round tin of 24 cm is 20 per cent wider than one of 20 cm, but the baking area is 44 per cent bigger: 24 times 24 divided by 20 times 20 is 1.44. A cake for a 20 cm tin therefore needs 1.44 times as much batter in a 24 cm tin to come out just as tall. For a rectangular tin you multiply length and width and divide the two areas: a baking dish of 20 by 30 cm has 600 cm² of base, a dish of 25 by 35 cm has 875, and that is almost one and a half times as much.

Baking time doesn't follow the factor. A thinner layer is done sooner and a thicker one takes longer, so check earlier than the recipe says. If you want to see how the quantities of a baking recipe scale, try banana bread.

What does Smaquli do with a recipe you adjust?

Smaquli works it out for you, from 1 to 20 people. Countable things become whole items and, where possible, halves, so ½ an onion but no ½ egg. Salt and spices scale more gently and grams and millilitres are rounded neatly: 1000 g becomes 1 kg. The quantities in the steps scale too, so the text gives the amount that fits your number of people.

If you go to more than twice or less than half the original number of people, you get a hint about the pan and the timings, with a button to have AI check the method. Adjusting the number of people is unlimited, even on Free. Checking the method you can do five times a month on Free, together with swapping ingredients. The rest is on Change servings. The app is in Dutch for now. English is on its way.