Density of water at 20 °C
| Value | 998.207 kg/m³ |
| Status | Measured: ± 0.002 kg/m³ (0.000002 relative) |
| Source | IAPWS-95; Kell (1975) for air-free water at 101.325 kPa |
| Categories | ThermodynamicMaterial Properties |
| microgram per liter | 998,207,000 μg/L |
| milligram per cubic meter | 998,207,000 mg/m³ |
| milligram per liter | 998,207 mg/L |
| pound per cubic yard | 1,682.5327 lb/yd³ |
| kilogram per cubic meter | 998.207 kg/m³ |
| gram per liter | 998.207 g/L |
| pound per cubic foot | 62.316027 lb/ft³ |
| pound per imperial gallon | 10.004443 lb/imp gal |
| pound per US gallon | 8.3304411 lb/gal |
| slug per cubic foot | 1.9368413 slug/ft³ |
| gram per cubic centimeter | 0.998207 g/cm³ |
| gram per milliliter | 0.998207 g/mL |
| kilogram per liter | 0.998207 kg/L |
| tonne per cubic meter | 0.998207 t/m³ |
| US short ton per cubic yard | 0.84126637 ton/yd³ |
| pound per cubic inch | 0.036062516 lb/in³ |
Water at any temperature
0 to 100 °CThe value above is one point on this curve. Liquid water from 0 to 100 °C at 1 atm — density, viscosity, specific heat, thermal conductivity and vapour pressure, all at the same state.
Learning zone
Twenty degrees is the conventional laboratory reference temperature, and 998.207 kg/m³ is the value glassware calibration, pipette gravimetry and specific gravity all rest on. Specific gravity is a ratio of densities, so it depends on which reference temperature the number was taken at — the common conventions are 20/20 °C, 20/4 °C and, in petroleum work, 60/60 °F.
Water expands with temperature above 4 °C, and by more than instinct suggests in heating systems: from 999.97 kg/m³ at 4 °C to 971.8 at 80 °C is a 2.9 % volume increase, which is precisely what an expansion tank has to absorb. A hydronic loop holding 2000 L at fill temperature will push roughly 50 L into the tank when it comes up to design temperature.