Water: Cups to Grams
Water is the one ingredient where cups and grams almost agree — and the small gap between the two published figures explains a lot about every other page on this site.
Water conversion table
| Cups | Grams | Ounces |
|---|
Why water is the reference liquid
Water is the ingredient every other conversion is secretly compared against, because its density is almost exactly 1 gram per millilitre. A US customary cup holds 236.588 mL, so a cup of water weighs almost exactly 237 g — the figure the USDA publishes and the one this converter uses. That neat relationship is also why the metric system is so convenient for liquids: fill any measuring jug to the 250 mL line with water and you are holding 250 g of it, near enough for any kitchen purpose.
Two honest numbers exist for a cup of water, and this page shows both. The USDA's published cup weight is 237 g. The King Arthur Baking chart lists 227 g, because it follows the old kitchen convention of treating a cup of liquid as 8 ounces — and 8 ounces by weight is 227 g. The convention is tidy but slightly under-measures real water by about 10 g per cup. This site uses 237 g for water only, and King Arthur figures for everything else; the main converter notes the exception right on the ingredient.
How to measure water and other liquids
Use a clear liquid measuring jug rather than a dry-ingredient cup: the spout and the extra headroom stop sloshing, and the markings are meant to be read from the side. Set the jug on a flat surface, pour, then crouch so your eye is level with the surface of the water and read the bottom of the meniscus — the slight curve where the water climbs the wall of the jug. Reading from above while the jug sits on the counter is the most common way home bakers accidentally pour 260 mL while aiming for 237.
For bread and baking, water is also the easiest ingredient to weigh: put the mixing bowl on the scale, tare it, and pour until the display shows the grams you need. Dough hydration is expressed in weights, so weighing water removes the meniscus question entirely — which is why this converter's grams-to-cups direction exists in the first place.
A cup of water in every cup size
Because water tracks volume so faithfully, it is the clearest way to see what the four cup types on this site actually mean. Each figure below is the USDA's 237 g scaled by the volume ratio of the cup:
| Cup type | Volume | Water weight |
|---|---|---|
| US customary cup | 236.588 mL | 237 g |
| US legal cup | 240 mL | 240 g |
| Metric cup | 250 mL | 250 g |
| UK imperial cup | 284.131 mL | 285 g |
Pick a different cup type in the converter above and the same scaling is applied to any liquid — milk, buttermilk and cream are in the dropdown because bakers swap between them constantly.
Frequently asked questions
How many grams is 1 cup of water?
237 grams on the USDA's published cup weight. The King Arthur Baking chart lists 227 g, following the convention that a cup of liquid equals 8 ounces by weight. This converter uses the USDA figure for water.
Is 1 cup of water 250 grams?
Only if your cup is a metric cup. A metric cup holds 250 mL, so it holds 250 g of water. A US customary cup holds 236.588 mL, which is 237 g of water — close, but not the same number.
Does hot water weigh less than cold water in a cup?
Very slightly — water expands as it warms, so a cup filled with hot water holds a touch less mass than the same cup filled cold. The difference is a few grams at most across normal kitchen temperatures and never matters in cooking; weigh or measure at whatever temperature the recipe uses.
Why do some websites say a cup of water is 236 or 240 grams?
They are rounding or using a different cup definition: 236 g is the volume in millilitres rounded down, 240 g matches the US legal cup used on nutrition labels, and 250 g matches the metric cup. The USDA's figure for a US customary cup is 237 g.
Related pages
- Milk: cups to grams — the other liquid in almost every bake — 227 g per cup on the King Arthur chart
- Honey: cups to grams — the heaviest common liquid, for contrast with water
- Cup volume conversions — cups to millilitres, fluid ounces and tablespoons for every cup type
Data sources: King Arthur Baking Ingredient Weight Chart and USDA FoodData Central. Weights are per US customary cup (236.588 mL); other cup sizes are scaled by volume ratio. See the data sources & method page for how values were chosen.