Water Density Calculator

Water Density vs Temperature

Water density is not constant — it changes with temperature. Pure water reaches its maximum density near 4 °C, then decreases as it warms toward boiling. This calculator uses a 5th-order polynomial to estimate density between 0 °C and 100 °C.

Formula

$$\rho(T) = \rho_0 + a_1 T - a_2 T^2 + a_3 T^3 - a_4 T^4 + a_5 T^5$$

Temperature $T$ is in °C. Coefficients: $\rho_0 = 999.83311$ kg/m³, $a_1 = 0.0752$, $a_2 = 0.0089$, $a_3 = 7.36413 \times 10^{-5}$, $a_4 = 4.74639 \times 10^{-7}$, $a_5 = 1.34888 \times 10^{-9}$.

To convert: 1 g/cm³ = 1000 kg/m³. At 20 °C, water density is approximately 998 kg/m³ (0.998 g/cm³).

Practical Notes

This formula applies to pure water at atmospheric pressure. Salt water, pressure, and dissolved gases change density. For seawater, use a dedicated salinity calculator.

Related tools: Water Viscosity Calculator and Density Calculator.

Frequently Asked Questions

Why does ice float on water?

Ice is less dense than liquid water because water expands when it freezes. At 0 °C, liquid water is denser than ice, so ice floats.

At what temperature is water most dense?

Pure water reaches maximum density at about 4 °C (roughly 1000 kg/m³). Above and below this point, density decreases.

How do I convert kg/m³ to g/cm³?

Divide by 1000. For example, 998 kg/m³ equals 0.998 g/cm³. Both units are numerically equal when expressed this way.

Does pressure affect water density?

Yes, but the effect is small at everyday pressures. This calculator assumes atmospheric pressure and pure water.

What is the density of water at room temperature?

At 20 °C, water density is approximately 998 kg/m³ or 0.998 g/cm³. At 25 °C, it is about 997 kg/m³.

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Water Density vs Temperature

Formula

Practical Notes

Frequently Asked Questions

Related Tools

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