Why cups to grams depends on the ingredient
People search for "cups to grams" expecting one number. It does not exist. Cups measure space; grams measure mass. Converting between them requires knowing how heavy the specific ingredient is for the space it takes up — its density.
The conversion is a density calculation
One US customary cup is 236.588 millilitres. To get grams you multiply that volume by the ingredient density. In practice we skip the physics and store one number per ingredient: grams per cup.
The spread is enormous. Puffed rice cereal is about 15 g per cup. Honey is about 340 g per cup. That is a factor of more than twenty for the exact same measuring cup.
| Ingredient | Grams per cup | Compared to water |
|---|---|---|
| Honey | 340 g | 1.44x heavier |
| Water | 236 g | baseline |
| Granulated sugar | 200 g | 0.85x |
| All-purpose flour | 125 g | 0.53x |
| Cocoa powder | 85 g | 0.36x |
| Rolled oats | 90 g | 0.38x |
| Shredded coconut | 80 g | 0.34x |
Weight units convert cleanly, volume units do not
Grams to ounces is pure arithmetic: divide by 28.3495. It works for anything, always, because both units measure mass.
Cups to grams is not arithmetic — it needs an ingredient. This is why generic converters that offer a single "cups to grams" box give wrong answers for most ingredients.
- Weight to weight (g, kg, oz, lb): ingredient-independent, exact.
- Volume to volume (cups, tbsp, tsp, ml, fl oz): ingredient-independent, exact.
- Volume to weight (cups to grams): ingredient-dependent, approximate.
Watch out for the two different cups
The US customary cup is 236.588 ml. The metric cup used in Australia and New Zealand is 250 ml — about 5.6% larger. UK recipes generally use weights, but older British books sometimes reference a 284 ml imperial cup.
We use the US customary cup throughout the site, because that is what American recipes — the ones people are usually converting — are written in.
| Cup | Volume | Used in |
|---|---|---|
| US customary | 236.588 ml | United States recipes |
| US legal (nutrition labels) | 240 ml | US packaging |
| Metric | 250 ml | Australia, New Zealand |
| Imperial (historic) | 284 ml | Older UK cookbooks |
When precision actually matters
- Baking: flour, sugar, butter and leaveners are chemistry. Weigh them.
- Bread: hydration is a weight ratio. Cups make it unknowable.
- Custards and caramel: sugar-to-liquid ratios decide whether they set.
- Soups, stews and stir-fries: measure however you like. A rough cup of chopped onion is fine.
Frequently asked questions
How many grams in a cup?
It depends entirely on the ingredient. Water is 237 g, flour is about 125 g, granulated sugar is about 200 g, and honey is about 340 g. Look up the specific ingredient rather than using a single number.
Is a gram of flour the same as a millilitre of flour?
No. Only water is close to 1 g per 1 ml. Flour is roughly 0.53 g per ml, so 100 ml of flour weighs about 53 g.
Why do different websites give different gram values?
Because they assume different filling methods and source data. A scooped cup of flour genuinely weighs more than a spooned one, so both 120 g and 145 g can be "correct" for different techniques. We publish the source behind every figure.
Can I just use 1 cup = 250 g for everything?
No — that is only close for water and thick liquids. Using it for flour would nearly double the amount.