Use this chemistry calculator to reproduce a named relationship with explicit quantities and units for study, laboratory planning, or an independent numerical check.

Vapor pressure (hPa)

Required number input.

Total pressure (hPa)

Required number input.

Compute the specific humidity in grams of water vapor per kilogram of moist air. The tool evaluates the supplied inputs together and returns the named outputs below; it does not infer omitted operating conditions or change the units shown.^[1]

Specific humidity (g/kg)

The resulting specific humidity returned as a number.

• Humidity and wet-bulb relationships depend on pressure, temperature scales, phase conventions, ventilation, and the selected saturation-vapor-pressure correlation. Local measurements and full psychrometric methods are needed for precision work.
• Use finite inputs in the displayed units and preserve more precision than the final presentation requires. Independently verify safety-critical, financial, compliance, or production decisions.

Check units and significant figures, compare the result with limiting cases, and use measured or source-specific constants where available. Laboratory, safety, and regulatory decisions require validated methods and appropriate uncertainty analysis.

• Mixing Ratio Calculator

  Compute the water vapor mass mixing ratio in grams per kilogram of dry air.

• Dewpoint From Vapor Pressure

  Invert the Magnus formula to compute dewpoint temperature from water vapor pressure.

• Heat of Neutralization Calculator

  Compute heat of neutralization per mole water formed.