Free WBGT calculator using ISO 7243 standards. Calculate workplace heat stress, flag conditions, and work-rest cycles for outdoor and indoor environments.
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Wet Bulb Globe Temperature (WBGT) is the gold standard for assessing heat stress risk in outdoor and indoor environments. Used by the military, OSHA, and sports organizations worldwide, WBGT combines air temperature, humidity, wind, and radiant heat to provide a comprehensive heat stress index.
WBGT (Wet Bulb Globe Temperature) is a composite temperature measurement that accounts for multiple environmental factors affecting heat stress: air temperature, humidity, wind speed, and solar radiation. It's more accurate than heat index alone because it considers radiant heat from the sun and cooling from wind.
WBGT Formulas
Outdoor: WBGT = 0.7×Tw + 0.2×Tg + 0.1×Td | Indoor: WBGT = 0.7×Tw + 0.3×TgOSHA and NIOSH recommend WBGT for assessing occupational heat exposure.
Sports organizations use WBGT to determine safe practice conditions.
Armed forces worldwide use the flag system to regulate training intensity.
Monitor conditions for outdoor workers to prevent heat illness.
Football, soccer, and other sports use WBGT for practice safety protocols.
Determine flag conditions and mandatory work-rest cycles for troops.
Factories and warehouses with heat exposure use WBGT for safety compliance.
White (78-82°F): Unrestricted activity. Green (82-85°F): Use discretion. Yellow (85-88°F): Limit strenuous activity. Red (88-90°F): Suspend intense activity. Black (>90°F): Cancel outdoor exertion.
WBGT accounts for solar radiation and wind, while heat index only uses temperature and humidity. WBGT is more accurate for outdoor work and sports because it considers all heat stress factors.
Globe temperature (Tg) is measured inside a black copper sphere that absorbs radiant heat like human skin. Our calculator estimates it from solar radiation and wind speed when a globe thermometer isn't available.
Military training often occurs in extreme conditions. WBGT and the flag system provide standardized guidelines for work-rest cycles, hydration, and activity modification to prevent heat casualties.