Scale and convert recipe measurements.
Scaling recipes is mostly linear: doubling servings means doubling ingredients. However, some elements don't scale linearly: spices and salt should be scaled to 1.5× when doubling (taste and adjust), leaveners (baking powder/soda) scale at 0.8× when doubling (too much causes collapse), and cooking time increases only slightly (a doubled casserole might need 10-15 more minutes, not double the time). Pan size matters more than ingredient scaling for baking. When halving a recipe calling for 1 egg, use 1 egg yolk or weigh: 1 large egg ≈ 50g, so use 25g. For odd fractions: ⅓ of ½ cup = 2 tbsp + 2 tsp. Always scale by weight (grams) when possible for maximum accuracy.