Weights and Measures: Accuracy and Conversion
Metric and imperial
Learn the core conversions. 1 kilogram = 1000 grams; 1 litre = 1000 millilitres. 1 ounce ≈ 28.35 g; 1 pound = 16 ounces ≈ 454 g; 1 pint ≈ 568 ml (UK) or 473 ml (US); 1 fluid ounce ≈ 28.4 ml. 1 tablespoon = 15 ml, 1 teaspoon = 5 ml, 1 dessertspoon = 10 ml. Kitchen questions usually expect the metric equivalents, so state your convention.
Weight versus volume
Dry ingredients must be weighed, not measured by volume, because density varies: a cup of flour and a cup of sugar differ in mass. Liquids may be measured by volume in a jug read at eye level on a flat surface. Yield and portion calculations: total weight ÷ portion size = number of portions. Edible portion (EP) differs from as-purchased (AP) weight because of trim and peel loss. EP = AP × yield percentage.
Scaling recipes
Scale by a factor: new quantity = original × (new yield ÷ old yield). Watch for ingredients that do not scale linearly - salt, leavening, strong spices, alcohol and setting agents - and for equipment capacity.
Temperature
Use Celsius in most BTEB contexts. 0 °C = 32 °F; 100 °C = 212 °F. Convert with F = (C × 9/5) + 32.
Worked example
A recipe serves 8 and uses 600 g of flour. You need 20 portions. Scale factor = 20 ÷ 8 = 2.5, so flour = 600 × 2.5 = 1500 g (1.5 kg). If you buy 2 kg of carrots with a 75% yield, EP = 2000 × 0.75 = 1500 g usable.
Traps
Mixing up tablespoons and dessertspoons; forgetting EP versus AP; rounding too early and compounding error; scaling salt and leavening linearly when they should be adjusted by taste and structure.