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Water Saturation Pressure Formula Comparison

Compare liquid-water and ice saturation-pressure fits across a bounded temperature range.

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Enter the known values in the units shown. Results update as you type.
Where results are editable, change one to solve backwards. Lock a value to hold it fixed.
Use the worked example to check the method. Reset restores the starting fields.

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At 0 °C, the Magnus, Tetens and Buck liquid estimates are 0.61094, 0.61078 and 0.61121 kPa, respectively.

Liquid fits: Antoine, Magnus, Tetens, Buck and a simplified exponential; ice fits: Tetens and Buck.

Enter these known values and leave the other values blank.

The supported range is −80 to 200 °C. Displayed formula branches retain their individual domains: ice below zero, liquid at or above zero, and the second Antoine coefficient set above 100 °C.
These are empirical approximations with different fitted ranges and uncertainties. Display does not establish equal accuracy at every temperature in the overall range.
Saturation pressure is a phase-equilibrium property, not current humidity or total atmospheric pressure. Water and ice fits differ.
Antoine and the simplified exponential calculate mmHg internally; other fits calculate kPa. Display conversions must be compared in the same pressure unit.
The Buck and ice Tetens source equations use 2.718281828459 as their rounded exponential base. This historical precision is retained.

Their fitted coefficients, phase assumptions and valid experimental ranges differ.

No. Actual vapor partial pressure is needed to calculate relative humidity.

Declare the physical or stated approximation domain; captured arithmetic is unchanged.