Water - Boiling Points at Vacuum Pressure
The boiling point of a substance is the temperature at which the vapor pressure of the liquid equals the pressure surrounding the liquid, and the liquid changes into a vapor. The boiling point of a liquid varies depending upon the surrounding pressure.
A liquid in a partial vacuum has a lower boiling point than when that liquid is at atmospheric pressure.
Online Water Boiling Point Calculator
The calculator below can be used to calculate the water boiling point at given, absolute pressures.
The output temperature is given as °C, °F, K and °R.
Note! ranges 0-1000 mbara, 0-14.7 psia, 0-760 mm Hg or 0-30 in Hg.
Choose the actual unit of pressure:
Below, figures and tables show the boiling point of water at varying vacuum .
See Water and Heavy Water for thermodynamic properties at standard condtions.
See also other properties of Water at varying temperature and pressure : Boiling points at high pressure , Density and specific weight , Dynamic and kinematic viscosity , Enthalpy and entropy , Heat of vaporization , Ionization Constant, pK w , of normal and heavy water , Melting points at high pressure , Prandtl number , Properties at Gas-Liquid Equilibrium Conditions , Saturation pressure , Specific gravity , Specific heat (heat capacity) , Specific volume , Thermal conductivity , Thermal diffusivity and Vapour pressure at gas-liquid equilibrium .
Boiling point as function of the pressure, given as "mm Hg below standard atmospheric pressure":
(= Vacuum of e.g. 100 mm Hg is the same as [760-100]=660 mm Hg absolute pressure)
The table shows the water boiling temperature at different vacuum pressure.
Vacuum is given as absolute pressure and pressure "below standard atmospheric pressure" (1 bara = 0 vacuum):
For full table with Vacuum and Water Boiling Point - rotate the screen!
| Absolute pressure | Vacuum (below standard atmospheric pressure) | Water boiling point | ||||||
| [Microns] [μm Hg] |
[in Hg] | [psia] | [mbara] [100*Pa] |
[in Hg] | [mmHg] [Torr] |
[mbar] [100*Pa] |
[°C] | [°F] |
| 760000 | 29.92 | 14.696 | 1013.3 | 0 | 0 | 0 | 100 | 212 |
| 635000 | 25.00 | 12.279 | 846.6 | 4.92 | 125.0 | 167 | 96 | 205 |
| 525526 | 20.69 | 10.162 | 700.6 | 9.23 | 234.4 | 313 | 90 | 194 |
| 500000 | 19.69 | 9.668 | 666.6 | 10.24 | 260.1 | 347 | 89 | 192 |
| 355092 | 13.98 | 6.866 | 473.4 | 15.94 | 404.9 | 540 | 80 | 176 |
| 233680 | 9.200 | 4.519 | 311.5 | 20.72 | 526.3 | 702 | 70 | 158 |
| 200000 | 7.874 | 3.867 | 266.6 | 22.05 | 560.1 | 747 | 67 | 152 |
| 149352 | 5.880 | 2.888 | 199.1 | 24.04 | 610.6 | 814 | 60 | 140 |
| 100000 | 3.937 | 1.934 | 133.3 | 25.98 | 659.9 | 880 | 52 | 125 |
| 92456 | 3.640 | 1.788 | 123.3 | 26.28 | 667.5 | 890 | 50 | 122 |
| 55118 | 2.170 | 1.066 | 73.48 | 27.75 | 704.9 | 940 | 40 | 104 |
| 31750 | 1.250 | 0.614 | 42.33 | 28.67 | 728.2 | 971 | 30 | 86 |
| 25400 | 1.000 | 0.491 | 33.86 | 28.92 | 734.6 | 979 | 27 | 80 |
| 22860 | 0.900 | 0.442 | 30.48 | 29.02 | 737.1 | 983 | 24 | 76 |
| 20320 | 0.800 | 0.393 | 27.09 | 29.12 | 739.6 | 986 | 22 | 72 |
| 17780 | 0.700 | 0.344 | 23.71 | 29.22 | 742.2 | 990 | 21 | 69 |
| 15240 | 0.600 | 0.295 | 20.32 | 29.32 | 744.7 | 993 | 18 | 64 |
| 12700 | 0.500 | 0.246 | 16.93 | 29.42 | 747.3 | 996 | 15 | 59 |
| 10160 | 0.400 | 0.196 | 13.55 | 29.52 | 749.8 | 1000 | 12 | 53 |
| 7620 | 0.300 | 0.147 | 10.16 | 29.62 | 752.3 | 1003 | 7 | 45 |
| 4572 | 0.180 | 0.088 | 6.10 | 29.74 | 755.4 | 1007 | 0 | 32 |
| 2540 | 0.100 | 0.049 | 3.39 | 29.82 | 757.4 | 1009.82 | -6 | 21 |
| 1270 | 0.050 | 0.025 | 1.69 | 29.87 | 758.7 | 1011.51 | -14 | 6 |
| 1000 | 0.039 | 0.019 | 1.33 | 29.88 | 759.0 | 1011.85 | -17 | 1 |
| 500 | 0.020 | 0.0097 | 0.67 | 29.90 | 759.5 | 1012.53 | -24 | -12 |
| 300 | 0.012 | 0.0058 | 0.40 | 29.91 | 759.7 | 1012.87 | -29 | -21 |
| 254 | 0.010 | 0.0049 | 0.34 | 29.91 | 759.7 | 1012.87 | -31 | -24 |
| 127 | 0.005 | 0.0025 | 0.17 | 29.92 | 759.8 | 1013.04 | -37 | -35 |
| 100 | 0.0039 | 0.0019 | 0.13 | 29.92 | 760.0 | 1013.21 | -40 | -40 |
| 50 | 0.0020 | 0.0010 | 0.07 | 29.92 | 760.0 | 1013.21 | -46 | -50 |
| 25.4 | 0.0010 | 0.0005 | 0.03 | 29.919 | 759.9 | 1013.17 | -51 | -60 |
| 12.7 | 0.0005 | 0.00025 | 0.017 | 29.9195 | 760.0 | 1013.19 | -57 | -70 |
| 2.54 | 0.0001 | 0.00005 | 0.003 | 29.9199 | 760.0 | 1013.20 | -68 | -90 |
- 0% vacuum = 760 torr = 14.7 psia = 29.92 in mercury abs = 101.4 kPa abs
- 50% vacuum = 380 torr = 7.3 psia = 15 in mercury abs = 50.8 kPa abs
- 99.9% vacuum = 1 torr = 0.01934 psia = 0.03937 in mercury abs = 1.3 kPa abs
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