Free online tool to calculate wet bulb temperature instantly. Essential for cooling tower sizing, evaporative cooling analysis, and WBGT monitoring. No sign-up required.
Wet bulb is how cold your skin gets when you sweat in a breeze. It’s the lowest temperature you can reach just by evaporating water.
Uses Stull (2011) approximation. Published validity: −20°C ≤ T ≤ 50°C, RH ≥ 5% at ≈101.325 kPa.
Rule of Thumb: Wet bulb is the absolute lowest temperature you can reach with a swamp cooler or cooling tower.
Checklist: Input ambient temp and humidity. The closer Wet Bulb is to Dry Bulb, the less effective evaporative cooling will be.
Quick Tip: A sustained wet bulb above 30°C (86°F) poses serious heat stress risks for outdoor workers and athletes.
Evaporation is a cooling process. As water evaporates from a wet wick, it removes heat, lowering the temperature unless the air is already at 100% humidity.
A sustained wet bulb temperature of 35°C (95°F) is considered the limit of human survivability, as the body can no longer shed heat through sweating.
Cooling towers use evaporation to cool water. The theoretical limit of how cold the water can get is the ambient wet bulb temperature, not the dry bulb.