Cups to Grams: Why the Conversion Depends on the Ingredient

Summary

A cup measures volume, not weight. Because different ingredients pack differently and have different densities, 1 cup of all-purpose flour weighs about 120 g, but 1 cup of honey weighs 336 g — nearly three times as much.

This calculator converts between volume measurements (cups, tablespoons, teaspoons, ml, fl oz) and weight measurements (grams, ounces, kg, lb) using ingredient-specific density values sourced from King Arthur Baking’s authoritative weight chart, the gold standard in US professional baking.

How it works

Why cups-to-grams varies by ingredient

Every ingredient has a different bulk density — how tightly its particles pack into a given volume. There are two reasons a cup of flour and a cup of sugar weigh differently:

1. Particle shape and size: Fine powders (icing sugar, cornstarch) pack more tightly than coarse grains (rolled oats, couscous). Irregular shapes (chopped nuts, rice) leave more air gaps.

2. Packing method: Scooping compacts an ingredient; spooning-and-levelling keeps it loose. A scooped cup of flour can weigh 25–30% more than a spooned cup.

The conversion formula

For non-cup volume inputs, we first convert to cups using exact US measurement relationships:

Volume unit relationships

These are US customary measurements. UK/Australian tablespoons (15 mL vs US 14.8 mL) and cups (250 mL vs US 236.6 mL) differ slightly; this calculator uses US standard measurements.

Worked example

Verification table

Values verified against King Arthur Baking weight chart (accessed 2026-02-24):

Measurement caveats

Flour: spoon-and-level vs scoop-and-sweep

This is the most important caveat in all of baking measurement:

• Spoon-and-level (King Arthur standard): Spoon flour into the cup, then level off. Result: ~120 g per cup.
• Scoop-and-sweep: Drag the measuring cup through the flour bag and level. Result: 140–160 g per cup — 17–33% more.

This calculator uses the spoon-and-level standard, matching King Arthur Baking. If your recipe is from a blog that scoops (many are), add ~10–15% to the gram value shown.

Brown sugar: packed vs unpacked

Standard recipes assume packed brown sugar. Press sugar firmly into the cup until it holds its shape when inverted.

• Packed: ~213 g per cup (King Arthur)
• Unpacked: ~100–120 g per cup

Powdered/icing sugar: sifted vs unsifted

• Unsifted (standard): ~113 g per cup
• Sifted: ~85–95 g per cup

Sift powdered sugar only if the recipe explicitly calls for it; most don’t.

Liquids: US vs metric cup

This calculator uses the US cup (236.6 mL). UK and Australian cups are 250 mL — about 5.6% larger. For liquids where density ≈ 1 g/mL, this means:

• 1 US cup water = 237 g
• 1 Australian/UK cup water = 250 g

Data sources and trust model

Every density value in this calculator comes from King Arthur Baking’s ingredient weight chart — the most comprehensive, publicly available, and professionally maintained baking weight reference in the US.

King Arthur Baking is a professional baking company with over 200 years of experience. Their weight chart is used by professional and home bakers as the industry standard.

If a value is wrong, it is because our source was wrong. We display the source for every ingredient so you can verify independently. The King Arthur weight chart is at: https://www.kingarthurbaking.com/learn/ingredient-weight-chart

Last verified: 2026-02-24.

Assumptions and limitations

• All values are for the US customary cup (236.6 mL / 8 fl oz)
• Flour values use the spoon-and-level method
• Brown sugar values assume packed
• Powdered sugar values are unsifted
• Honey, maple syrup, and other syrups at room temperature (viscosity affects pouring but not density)
• Values are averages — brand variation, humidity, and altitude can cause minor differences (typically ±2–5%)
• Cooked/prepared ingredient weights (e.g., cooked rice) differ from raw; this calculator shows raw/dry weights unless noted