There is no single answer because a cup measures volume, not weight — one US cup is about 236 grams of water, roughly 120–125 grams of all-purpose flour, and about 200 grams of granulated sugar, so grams per cup depend entirely on the ingredient.
“How many grams in a cup” is one of the most common kitchen questions, and the honest answer surprises people: it changes with what you are measuring. A cup is a unit of volume (how much space something takes up), while a gram is a unit of mass (how much it weighs). Light, fluffy ingredients weigh far less per cup than dense ones.
Why a cup does not have a fixed gram weight
Density is the reason. A cup of feathers and a cup of lead occupy the same space but weigh wildly different amounts, and the same principle applies in the kitchen. All-purpose flour is airy and settles unevenly, so a cup can range from about 120 to 145 grams depending on whether it is spooned in lightly or scooped and packed. Granulated sugar is denser and more consistent. Water is the reference point, because by definition one milliliter of water weighs almost exactly one gram.
Grams per US cup for common ingredients
The table below gives typical weights for one US customary cup (about 236.6 milliliters). Baking references vary slightly, so treat these as reliable working figures rather than exact constants. This is a reference chart, not medical or nutritional advice.
| Ingredient (1 US cup) | Approx. grams | Notes |
|---|---|---|
| Water | 236 g | The density reference; 1 mL ≈ 1 g |
| Milk (whole) | ~245 g | Slightly denser than water |
| All-purpose flour | 120–125 g | Spooned and leveled; scooping adds weight |
| Bread flour | ~127 g | Slightly heavier than all-purpose |
| Granulated (white) sugar | ~200 g | Consistent and dense |
| Packed brown sugar | ~213 g | Pressed firmly into the cup |
| Powdered (confectioners) sugar | ~120 g | Sift before measuring for accuracy |
| Butter | ~227 g | Equal to two US sticks (8 oz) |
| Rolled oats | ~90 g | Light and airy |
| Uncooked white rice | ~185 g | Long-grain, unpacked |
| Honey | ~340 g | Very dense; far heavier than water |
US cups versus metric cups
“Cup” is not even one fixed volume worldwide, which adds another layer of variation:
| Cup type | Volume | Water weight |
|---|---|---|
| US customary cup | 236.6 mL | ~236 g |
| US legal cup (nutrition labels) | 240 mL | ~240 g |
| Metric cup (Australia, etc.) | 250 mL | ~250 g |
Most American recipes assume the 236.6 mL customary cup, but nutrition labels in the US use a rounded 240 mL cup, and Australian and many other metric recipes use a 250 mL cup. The differences are small for a single cup but compound in larger batches.
Why weighing beats measuring by volume
Professional bakers weigh ingredients because it removes the guesswork that comes from how you fill a cup. Two cooks measuring “one cup of flour” can end up 20 percent apart simply because one packs the cup and the other spoons it lightly. A cheap digital kitchen scale set to grams eliminates that inconsistency, and it is faster because you can measure several ingredients into one bowl. If a recipe gives both cups and grams, use the grams.
How to measure a cup accurately when you must
- For dry ingredients, use a flat-topped dry measuring cup, not a liquid measuring jug.
- Stir the flour or sugar first to loosen it, then spoon it into the cup rather than scooping.
- Level the top with the straight edge of a knife — do not tap or pack unless the recipe says “packed.”
- For liquids, use a clear liquid measuring cup and read it at eye level.
How the same cup weighs different amounts
It is worth seeing the range in concrete terms. A single US cup holds about 236 grams of water but only about 90 grams of rolled oats and a hefty 340 grams of honey. That is nearly a fourfold spread for the exact same volume, driven purely by how tightly packed and heavy each substance is. Flour sits at the light end and thickens the confusion because its weight also shifts with humidity, how long it has sat in the bag, and whether it has been sifted. This is precisely why substituting one flour for another cup-for-cup can change a recipe: whole wheat, bread, and cake flours do not all weigh the same per cup.
Common baking scenarios
- Doubling a recipe. Small per-cup differences double too, so weighing keeps a scaled-up batch true to the original ratios.
- Converting a European recipe. Recipes from the UK and Europe usually list grams already; resist the urge to translate them into cups, since you lose accuracy going from a precise weight to an approximate volume.
- Sticky ingredients. Honey, syrup, and peanut butter are hard to measure cleanly by volume; weighing them straight into the bowl avoids waste and mess.
Converting between cups and smaller units
If your recipe mixes units, it helps to know how a cup breaks down. One US cup is 8 fluid ounces by volume and 16 tablespoons; our guides on how many ounces are in a cup and how many tablespoons are in a cup cover those breakdowns in detail. For weight-based ingredients you can also work from smaller units using how many grams are in an ounce, and for scaling recipes up, how many cups are in a quart is a handy companion.
The bottom line
Whenever a recipe matters — especially in baking, where ratios drive the result — look up the specific ingredient rather than assuming a universal grams-per-cup number, or better yet weigh it. Volume-to-weight conversion is only ever an approximation, so build in a little tolerance and lean on a scale for anything where precision counts.
