How to scale a recipe without ruining it
Scaling is arithmetic plus judgement. Here is the method professional kitchens use.
Try it on a recipe1. Find the conversion factor
Divide what you need by what the recipe makes. Need 30 portions from a recipe for 12? 30 ÷ 12 = 2.5.
2. Convert everything to weight
Cups and spoons multiply badly. Convert to grams and millilitres first, scale, then convert back only if you must.
3. Be careful with salt, leavening and spice
These rarely scale 1:1 at large factors. Start at around 85% of the straight conversion and adjust after tasting or a test bake.
4. Round count items sensibly
2.5 eggs is two eggs plus half a beaten egg (about 25 g). For large batches, weigh eggs instead of counting.
5. Match pan size and depth
Use surface area, not diameter. A 25 cm round has about 1.56× the area of a 20 cm round, not 1.25×.
6. Adjust time, not just quantity
Larger volumes heat slowly. Bake and simmer times change less than you think — use temperature and doneness checks.