Changing a recipe’s yield is more than multiplying every number. Ingredient ratios matter, but so do pan size, surface area, equipment capacity, seasoning, and cooking time.
1. Choose a scale factor
Divide the desired yield by the original yield. A recipe serving 4 that needs to serve 6 has a scale factor of 1.5. Multiply each ingredient by that factor. Write the new quantities down before you begin rather than doing arithmetic while cooking.
2. Watch awkward measurements
Half of 1 tablespoon is 1 1/2 teaspoons. Half of 3/4 cup is 3/8 cup, which is easier to measure as 1/4 cup plus 2 tablespoons. A kitchen scale avoids many awkward fractions.
3. Treat seasoning cautiously
Salt, hot peppers, extracts, smoke flavor, and strong spices do not always need to increase in a perfectly straight line. Start with somewhat less than the calculated amount, especially in large batches, then taste and adjust when safe to do so.
4. Match pan capacity and depth
Doubling a casserole in the same pan makes it deeper and can increase cooking time dramatically. Two pans of the original size often produce a more predictable result. For cakes and quick breads, changing pan shape affects both depth and exposed surface area; avoid filling a pan more than the recipe or manufacturer recommends.
5. Do not automatically double cooking time
Two trays of cookies usually need about the same baking time as one tray, though airflow may change. A larger roast, deeper casserole, or bigger pot of soup may need longer. Use doneness cues and a thermometer where appropriate.
6. Be careful with baking and candy
Yeast dough, cakes, candy, jam, and pressure-cooker recipes can be sensitive to batch size and equipment limits. Check bowl, mixer, pot, canner, and pressure-cooker capacity before scaling. For preservation recipes, use a current tested recipe from a reliable canning authority rather than changing ingredient ratios.