Water Cups to Grams
One US cup of water is approximately 237 g in this rounded volume-and-density kitchen reference; the old USDA FoodData Central claim was not directly verifiable.
Reference measurement
237 grams per US cup
Pour into a liquid US cup and read the meniscus at eye level.
NIST rounds one US measuring cup to about 237 mL; using USGS' approximate water density of 1 g/mL gives about 237 g per cup. Source note
The 237 g kitchen reference is rounded; actual density varies slightly with temperature.
Common Water measurements
| US cups | Grams |
|---|---|
| 0.25 US cups | 59.25 grams |
| 0.333 US cups | 79 grams |
| 0.5 US cups | 118.5 grams |
| 0.667 US cups | 158 grams |
| 0.75 US cups | 177.8 grams |
| 1 US cup | 237 grams |
| 1.5 US cups | 355.5 grams |
| 2 US cups | 474 grams |
Practical examples
- 1/2 US cup = 118.5 grams.
- 1 US tablespoon = 14.81 grams.
- 3 US teaspoons = 14.81 grams.
Measuring note
Pour into a liquid US cup and read the meniscus at eye level.
The 237 g kitchen reference is rounded; actual density varies slightly with temperature.
The water mass is an approximation derived from volume
NIST's official capacity table defines a measuring cup as eight US fluid ounces and rounds its volume to 237 mL. USGS's water-density guide describes the common kitchen approximation of 1 gram per milliliter, with actual density changing by temperature. About 236.6 mL × about 1 g/mL gives approximately 236.6 g, rounded to 237 g.
At roughly 21°C, the USGS table shows around 0.99802 g/mL, which makes the same 236.6 mL cup about 236.1 g in physical mass. The 237 g model is deliberately an everyday whole-gram estimate, not a precision water measurement at every temperature.
Another baking reference prints 227 g for water
King Arthur's baking-weight chart instead lists one cup of water at eight ounces by weight, or 227 g. That is about 10 g below this volume-and-density approximation. Without verified original documentation explaining King Arthur's measurement method, we do not invent the cause or combine the two chart values.
At 1½ cups this calculator uses 355.5 g. If your recipe specifies water mass or a precise hydration ratio, retain its stated grams. The previously linked USDA FoodData Central record could not be read directly and is not presented as an independently confirmed source for 237 g per cup.