Heat Stress Calculator (WBGT)
ACGIH TLV / Action Limit Work-Rest Recommendation
Method:
Wet Bulb Globe Temperature (WBGT) — the ISO 7243 standard heat-stress index used by ACGIH, NIOSH, and OSHA. Combines temperature, humidity, radiant heat, and wind into a single value.
⚠ Important — Screening Tool, Not Compliance
Heat-related illness can be life-threatening. This tool provides screening estimates based on ACGIH 2024 TLV / Action Limit values for educational and planning purposes only. The “estimate from temp + humidity” mode uses the Australian Bureau of Meteorology simplified outdoor formula and is less accurate than direct WBGT measurement. Always follow your employer’s heat illness prevention plan and seek medical care for any symptoms. The author and FieldSafetyTalk.com assume no liability for decisions made using this tool.
1. WBGT Reading
1. Environmental Conditions
2. Worker & Workload
Please enter valid temperature and humidity values.
Effective WBGT
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ACGIH limits at this workload
TLV (acclimatized worker, continuous work)
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Action Limit (unacclimatized, continuous work)
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Recommended work : rest (per hour)
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Source: ACGIH 2024 TLVs and BEIs — Heat Stress and Strain (Table 2); ISO 7243; OSHA Technical Manual III-4. Estimation mode uses Australian Bureau of Meteorology simplified WBGT formula (outdoor average daytime conditions).
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