Water Density by Temperature
Quick values (pure, air-free VSMOW water, Tanaka 2001): 4 °C = 999.975 kg/m³ (maximum) · 15 °C = 999.103 · 20 °C = 998.207 kg/m³ (0.99821 g/mL) · 25 °C = 997.047 kg/m³ (0.99705 g/mL) · 30 °C = 995.649 · 40 °C = 992.215 kg/m³.
The density of pure water is the reference in science and industry for calibrating volumetric glassware, density meters and flow meters. This calculator uses the formula by M. Tanaka et al. (Metrologia, 2001), approved by the CIPM (International Committee for Weights and Measures) for temperatures from (0 to 40) °C. Enter the temperature in °C to get the density in kg/m³ and g/mL; the relative standard uncertainty of the formula is of the order of 1×10⁻⁵.
The Tanaka formula used by this calculator omits the corrections for dissolved air and compressibility (it applies at 101.325 kPa). The constant a5 = 999.974950 kg/m³ corresponds to pure water with the VSMOW isotopic composition (Vienna Standard Mean Ocean Water). Distilled or deionized water can differ by a few thousandths of a kg/m³ due to its isotopic abundance; seawater or water with dissolved salts is denser and is not calculated with this formula.
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Water density table by temperature
Pure water (VSMOW), air-free, at 101.325 kPa. Tanaka formula (2001):
0 °C = 999.8428 kg/m³ = 0.99984 g/mL
1 °C = 999.9017 kg/m³ = 0.99990 g/mL
2 °C = 999.9429 kg/m³ = 0.99994 g/mL
3 °C = 999.9672 kg/m³ = 0.99997 g/mL
4 °C = 999.9749 kg/m³ = 0.99997 g/mL
5 °C = 999.9668 kg/m³ = 0.99997 g/mL
6 °C = 999.9431 kg/m³ = 0.99994 g/mL
7 °C = 999.9045 kg/m³ = 0.99990 g/mL
8 °C = 999.8513 kg/m³ = 0.99985 g/mL
9 °C = 999.7839 kg/m³ = 0.99978 g/mL
10 °C = 999.7027 kg/m³ = 0.99970 g/mL
11 °C = 999.6081 kg/m³ = 0.99961 g/mL
12 °C = 999.5005 kg/m³ = 0.99950 g/mL
13 °C = 999.3801 kg/m³ = 0.99938 g/mL
14 °C = 999.2474 kg/m³ = 0.99925 g/mL
15 °C = 999.1026 kg/m³ = 0.99910 g/mL
16 °C = 998.9459 kg/m³ = 0.99895 g/mL
17 °C = 998.7778 kg/m³ = 0.99878 g/mL
18 °C = 998.5984 kg/m³ = 0.99860 g/mL
19 °C = 998.4079 kg/m³ = 0.99841 g/mL
20 °C = 998.2067 kg/m³ = 0.99821 g/mL
21 °C = 997.9950 kg/m³ = 0.99800 g/mL
22 °C = 997.7730 kg/m³ = 0.99777 g/mL
23 °C = 997.5408 kg/m³ = 0.99754 g/mL
24 °C = 997.2988 kg/m³ = 0.99730 g/mL
25 °C = 997.0470 kg/m³ = 0.99705 g/mL
26 °C = 996.7857 kg/m³ = 0.99679 g/mL
27 °C = 996.5151 kg/m³ = 0.99652 g/mL
28 °C = 996.2353 kg/m³ = 0.99624 g/mL
29 °C = 995.9465 kg/m³ = 0.99595 g/mL
30 °C = 995.6488 kg/m³ = 0.99565 g/mL
31 °C = 995.3424 kg/m³ = 0.99534 g/mL
32 °C = 995.0275 kg/m³ = 0.99503 g/mL
33 °C = 994.7041 kg/m³ = 0.99470 g/mL
34 °C = 994.3724 kg/m³ = 0.99437 g/mL
35 °C = 994.0326 kg/m³ = 0.99403 g/mL
36 °C = 993.6847 kg/m³ = 0.99368 g/mL
37 °C = 993.3290 kg/m³ = 0.99333 g/mL
38 °C = 992.9654 kg/m³ = 0.99297 g/mL
39 °C = 992.5941 kg/m³ = 0.99259 g/mL
40 °C = 992.2152 kg/m³ = 0.99222 g/mL
Above 40 °C (IAPWS reference values, outside the Tanaka range):
50 °C ≈ 988.0 kg/m³
60 °C ≈ 983.2 kg/m³
70 °C ≈ 977.8 kg/m³
80 °C ≈ 971.8 kg/m³
90 °C ≈ 965.3 kg/m³
100 °C ≈ 958.4 kg/m³
How is it used in metrology?
It is the basis of gravimetric calibration of volumetric equipment (pipettes, burettes, flasks and gravimetric flow meters): volume is obtained by dividing the mass of water by its density at the measured temperature. A 1 °C temperature error is about 0.02 % in volume at 20 °C. Weighing also needs an air buoyancy correction based on air density, and for temperatures between two table values you can use linear interpolation.
Frequently asked questions
Should I correct for dissolved air?
Yes, for high-accuracy work: air-saturated water is about 0.0025 kg/m³ less dense between 0 and 25 °C.
And for pressure?
Water compresses about 0.046 kg/m³ for every 100 kPa above standard atmospheric pressure.
Why is maximum density near 4 °C?
Because of hydrogen bonding: below 3.98 °C water starts arranging into a more open structure and its density drops.
What is the density of water in g/mL or g/cm³?
Between 0 and 10 °C it is practically 1.000 g/mL; at 20 °C it is 0.99821 g/mL and at 25 °C, 0.99705 g/mL. 1 g/mL = 1 g/cm³ = 1000 kg/m³.
What is the density of seawater?
About 1025 kg/m³ at the surface (usually between 1020 and 1030 kg/m³), depending on salinity and temperature. It is not calculated with the Tanaka formula, which is only for pure water.
What is the density of water at 100 °C?
About 958.4 kg/m³ (0.9584 g/mL) at atmospheric pressure, roughly 4 % less than at 4 °C.