Psychrometric Calculator

Solve a browser-local moist-air state from dry bulb + RH, dry bulb + dew point, dew point + RH, or dry bulb + wet bulb, with pressure-aware outputs.

Define the moist-air state

Choose a common pair of independent humidity inputs. Station pressure is used for wet-bulb, humidity-ratio, enthalpy and specific-volume estimates.

Input pair

Display temperature

Dry-bulb temperature

Relative humidity (%)

Station pressure (hPa)

Quick state

This is a compact psychrometric calculator, not a replacement for a calibrated psychrometer or a full standards-based HVAC design package. Formula approximations and pressure assumptions are shown rather than hidden.

Psychrometric Calculator Dew Point Relative Humidity Absolute Humidity Wet Bulb

Calculated properties

—Dry bulb

—Relative humidity

—Dew point

—Wet bulb

Psychrometric Calculator: Dew Point, Wet Bulb & Enthalpy

Solve moist-air properties from common input pairs, apply altitude-based pressure, and visualize the state with dew point, wet bulb and enthalpy context.

Site altitude (ft)

Surface temperature

Use the tool above, then review this deeper calculation.

Mini psychrometric state plot

Plot the calculated dry-bulb temperature and humidity ratio against approximate 20/40/60/80/100% RH guide curves at the current station pressure.

—Current state

—Humidity ratio

—Station pressure

This compact plot is an approximate visualization for orientation and cross-checking. Use the numeric properties above for values and qualified psychrometric methods where design certification is required.

One moist-air state, several related properties

Relative humidity, dew point, wet bulb, vapor pressure, absolute humidity and humidity ratio describe different parts of the same moisture state. WebToolArc keeps the selected inputs visible and shows related outputs together instead of treating the terms as interchangeable.

Accuracy boundary

These browser calculations use standard psychrometric approximations. Real measurements can differ because of sensor calibration, station pressure, ventilation, radiation, local gradients and the exact saturation-vapor-pressure formulation. Use calibrated instruments and applicable engineering or meteorological standards when decisions require certified measurements.

Practical guide and verification

Pressure belongs with the moist-air state

Humidity ratio, wet-bulb temperature, enthalpy and specific volume depend on station pressure. Use pressure appropriate to the site rather than assuming sea-level pressure when altitude is significant, and keep that pressure with any exported or copied state.

Use the mini plot to see relationships, not to replace the numeric result

The state marker and relative-humidity guide curves help show where the air lies relative to saturation. Read exact values from the calculated properties; the compact chart is an approximate visualization rather than a standards-certified psychrometric chart.

Dew point is the direct condensation comparison

For a surface-condensation check, compare the calculated dew point with the measured surface temperature. A surface below dew point can support condensation even when room relative humidity does not appear unusually high.

Different input pairs should resolve to one consistent state

Dry bulb plus RH, dry bulb plus dew point and other supported pairs describe the same moist-air state when measurements are consistent. Solving from an alternate measured pair is a useful cross-check when independent sensors are available.

Measurement uncertainty can dominate formula precision

Sensor calibration, air stratification, radiation, response time and pressure error can exceed the rounding shown by the browser. Keep instrument quality and sampling location in mind before interpreting small differences between two calculated states.