Work out heat stress (wbgt) instantly with clear inputs, formula shown and shareable results.
Wet bulb globe temperature combines humidity, radiant heat and air temperature into one index. Outdoors with solar load it is 0.7 natural wet bulb plus 0.2 globe plus 0.1 dry bulb; indoors the dry bulb term drops out and the globe weighting rises. The heavy weighting on wet bulb reflects that evaporative cooling is the body's main defence.
WBGT outdoors
WBGT = 0.7 Tnwb + 0.2 Tg + 0.1 Tdb
WBGT indoors
WBGT = 0.7 Tnwb + 0.3 Tg
Preliminary estimate only. Heat stress assessment must follow the applicable standard, account for clothing and metabolic rate, and be supervised by a competent person.
WBGT = 0.7 Tnwb + 0.2 Tg + 0.1 Tdb. Wet bulb globe temperature combines humidity, radiant heat and air temperature into one index.
Because a humid 30 °C is far more dangerous than a dry 35 °C. Sweat cannot evaporate in high humidity, so the body loses its main cooling mechanism regardless of air temperature.
This calculator takes 4 inputs: Natural wet bulb temperature, Globe temperature, Dry bulb temperature, Exposure location. The pre-filled defaults are a realistic worked example — replace them with your own site or project figures.