Home › Health › WBGT & Heat Index calculator

🌡️ WBGT & heat index work/rest calculator

Compute the NWS Heat Index and Wet Bulb Globe Temperature (WBGT), then get an ACGIH 2026 TLV / Action-Limit work-rest schedule, hydration target, risk band, a 5-day acclimatization ramp and OSHA Heat NEP guidance. Enter air temperature and humidity, or measured natural-wet-bulb and globe temperatures for true WBGT. Exports to Word.

Environment

Dry-bulb air temperature (°F)

Relative humidity (%)

Sun / radiant exposure

Measured WBGT (optional — overrides the estimate)

Natural wet-bulb Tnwb (°C)

Globe temperature Tg (°C)

Outdoor / solar load (use the 0.7/0.2/0.1 formula)

Work & worker

Workload (metabolic rate)

Clothing adjustment (CAV, +°C to WBGT)

Acclimatization status

Worker body weight (lb, for water target)

⚠️ Educational estimate only — NOT legal, medical, or occupational-hygiene advice. This calculator implements public formulas (NWS Rothfusz Heat Index, a Bernard/ACGIH-style WBGT estimate, and ACGIH 2026 TLV/Action-Limit work-rest tables). Estimated WBGT from temperature and humidity is approximate; for compliance decisions measure WBGT with a calibrated instrument and have a qualified safety professional or industrial hygienist set work-rest cycles for your site. Verify the current-year ACGIH TLV, NIOSH criteria and OSHA Heat NEP with the source documents.