Water Density Calculator
Enter a water temperature to calculate its density, since water's density changes slightly (and non-linearly) with temperature.
Last updated: September 5, 2026
Frequently asked questions
What is the density of water at room temperature?
About 998.2 kg/m³ (0.9982 g/cm³) at 20°C, which is commonly used as "room temperature" - very close to, but not exactly, the commonly rounded figure of 1,000 kg/m³ (1 g/cm³) used in everyday estimates.
Why isn't water's density exactly 1,000 kg/m³ except at one specific temperature?
1,000 kg/m³ (1 g/cm³) is only exact at 3.98°C, water's point of maximum density - a quirk caused by hydrogen bonding effects that make water denser as it warms from 0°C up to about 4°C, before behaving normally and getting less dense as it warms further.
Does salt water have the same density as this calculator shows?
No - this calculator is for pure (fresh) water only. Seawater is denser due to dissolved salts, typically around 1,020-1,029 kg/m³ at the surface depending on salinity and temperature, meaningfully higher than fresh water at the same temperature.
Where can I find the density of the water at a specific temperature?
Enter that temperature above and this calculator gives you the density directly, interpolated from standard reference values between 0°C and 100°C - no need to look it up in a printed table.
What is the density of boiling water (100°C)?
About 958.4 kg/m³ - notably lower than water's density at room temperature (998.2 kg/m³ at 20°C), since water expands and becomes less dense as it's heated toward its boiling point.
Why would I need to know water's density at different temperatures?
Precise density matters for calibrating lab instruments, calculating buoyancy, converting between volume and mass in scientific or brewing contexts, and hydraulic engineering - everyday uses like cooking rarely need more precision than the standard 1 kg/liter approximation.
Does altitude or air pressure affect water's density?
Only very slightly under normal conditions - pressure has a much smaller effect on liquid water's density than temperature does, since water is nearly incompressible. This calculator accounts for temperature only, which is the dominant factor for everyday and most scientific purposes.