What This Calculator Does
Wet bulb temperature is the lowest temperature air can reach through evaporative cooling. It’s an important measure for assessing heat stress risk, since high wet bulb temperatures mean sweat evaporates less effectively.
The Formula
This calculator uses the Stull (2011) empirical approximation, a widely cited formula that estimates wet bulb temperature directly from dry-bulb temperature (T, in °C) and relative humidity (RH, in %) without needing pressure data or iterative solving.
Note: The Stull formula is most accurate for temperatures between about -20°C and 50°C and relative humidity from 5% to 99% at sea-level-like pressures. This tool is for general educational and planning use, not a substitute for official heat-safety guidance.
Last reviewed August 2026