Units & Conversion · 杯与克（Cup & Gram） · Updated 2026-10-25
What Is Cup & Gram?
Definition
A cup is volume (US 237 mL, imperial 284 mL); converting to grams needs the ingredient's density: sifted flour ~120g/cup (packed up to 150g), granulated sugar 200g, packed brown sugar 220g, butter 227g, water/milk 237g. Baking is stoichiometry — a 10% flour error turns bread into mantou. Serious recipes weigh in grams with a scale; American recipes scoop cups; the scale is the only reliable bridge between "to taste" and cups.
Formula
Weight (g) = Volume (mL) × density (g/mL)
Worked Example
A recipe calling for 2 cups of flour scoops ~240g but packs up to 300g — a 25% spread. Writing "240g flour" removes all ambiguity.
Common Misconception
"1 cup = 250g of anything" — only water is close; converting flour at 250g/cup doubles the flour and turns cake into pancake. The liter/kilogram confusion is the same: 1L of honey ≈1.4kg while 1L of oil ≈0.92kg — density rules weight.
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