Vapor Pressure Calculator

Compare saturation vapor pressure, actual vapor pressure, and vapor-pressure deficit locally.

Air temperature (°C)

Relative humidity (%)

Optional dew point (°C)

—Saturation vapor pressure

—Actual vapor pressure

—Vapor-pressure deficit

—Derived RH

Weather calculations run locally in your browser. These tools transform observations with stated formulas; they do not replace official forecasts, alerts, measurements, or professional field instruments.

How to use this Vapor Pressure Calculator

Calculate saturation and actual water-vapor pressure from temperature, dew point, or relative humidity. Enter your values above and the result is calculated directly in your browser. No account is required.

Fast answer, clear inputs

This tool is built around one job: give the answer quickly without forcing a signup or hiding the result. Related tools are linked nearby when the next calculation or conversion is useful.