Calculate saturation vapor pressure from temperature or reverse-solve temperature with built-in and custom Antoine constants, full unit conversions, range checks, and sensitivity.

Pure-component correlation only. Constants and fit range must match the exact logarithm and units; this is not a process-safety calculation.

Pressure From Antoine Equation Formula

The following example problem outlines the steps and information needed to calculate the Pressure From the Antoine equation.

P = 10 ^ (A - (B / (C + T)))

Variables:

  • P is the saturation vapor pressure. Custom constants in this calculator must use log10(P/mmHg) = A − B/(T/°C + C); do not enter bar/K constants unchanged.
  • A, B, and C are Antoine constants for a given substance (they depend on the pressure and temperature units used); T is the temperature (typically in °C for this form).

How to Calculate Pressure From Antoine Equation?

The following steps outline how to calculate the Pressure From the Antoine equation.

  1. Choose a preset or enter custom Antoine constants A, B, C and their valid temperature range. The water preset covers 1–100 °C; ethanol −57–80 °C; benzene 14.55–80.92 °C. The benzene set is converted from the NIST Chemistry WebBook bar/K fit. Stay within the fitted range; this pure-component correlation does not describe mixtures.
  2. Next, gather the formula from above = P  = 10 ^ (A- (B/(C+T))).
  3. Finally, calculate the Pressure From the Antoine equation.
  4. After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem : 

Use the following variables as an example problem to test your knowledge.

A = 8, B = 1708, C = 233, and T = 99 Â°C

P = 10^(8 − 1708/(233 + 99)) ≈ 716.8391 mmHg ≈ 95.5707 kPa. Select Custom and enter these constants with temperature 99 °C. This is an algebraic example with no supplied substance or fit range; it does not establish physical validity. For the inverse calculation use T = B/[A − log10(P/mmHg)] − C.