Wet-Bulb Temperature Calculator

About this calculator

This calculator estimates wet-bulb temperature (Tw) from air temperature and relative humidity using Stull's formula, an arctangent-based empirical approximation from 2011 that's accurate to within about 0.3°C for typical conditions without needing a psychrometric chart. Wet-bulb temperature reflects the lowest temperature achievable through evaporative cooling.

Meteorologists, occupational health officers, and outdoor-event organizers use it to gauge heat stress risk — wet-bulb readings above roughly 32°C (90°F) signal dangerous conditions where sweat can no longer cool the body effectively. Enter the air temperature and relative humidity to get the wet-bulb temperature.