How-To Guides6 min readJanuary 2026

How to Calculate Heat Index for Workplace Safety

Don't rely on the bank thermometer. Here is how to measure the real heat exposure on your jobsite.

Temperature vs Heat Index

Heat Index combines air temperature and relative humidity. It tells you how hot it FEELS.

Tools You Need

  • An accurate digital hygrometer/thermometer.
  • The OSHA Heat Safety Tool App (or HeatShield PRO dashboard).

The Formula

Don't do the math yourself. Use the NWS chart. If Temp is 90°F and Humidity is 60%, Heat Index is 100°F (Danger!).

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