---
title: "What Is Heat Index Work Rest Chart? Heat Stress and Hydration Glossary"
description: "A heat index work/rest chart links the heat index to how long crews can work and how long they should rest."
url: https://jmarsolutions.multisites.ai/glossary/heat-index-work-rest-chart
publisher: JMAR Solutions
phone: +1-214-632-7780
quote: https://jmarsolutions.multisites.ai/contact
---

Measurement

# Heat index work rest chart

A heat index work/rest chart links the heat index to how long crews can work and how long they should rest. Charts differ, so use the one your safety program adopts.

A heat index work/rest chart pairs a heat index reading with a suggested split of work time and rest time. Hotter readings mean longer or more frequent breaks. Many charts also factor in the workload.

OSHA notes the NIOSH/OSHA Heat App gives only the heat index, not WBGT, though it also gives workload guidance. OSHA says workers should generally take hourly breaks when heat stress passes its limits. Break length depends on heat, workload and a cool place to rest. A chart is a starting point. Sun, gear and [acclimatization](https://jmarsolutions.multisites.ai/glossary/acclimatization) change the real risk. See our [work/rest chart guide](https://jmarsolutions.multisites.ai/guides/heat-index-work-rest-chart), and the terms [heat index](https://jmarsolutions.multisites.ai/glossary/heat-index) and [work/rest schedule](https://jmarsolutions.multisites.ai/glossary/work-rest-schedule).

[From JMAR SolutionsHydration programs and toolbox talks for crews](https://jmarsolutions.multisites.ai/hydration-programs)

## Related terms

-   [Heat index](https://jmarsolutions.multisites.ai/glossary/heat-index)
-   [Work/rest schedule](https://jmarsolutions.multisites.ai/glossary/work-rest-schedule)
-   [WBGT](https://jmarsolutions.multisites.ai/glossary/wbgt)
-   [Acclimatization](https://jmarsolutions.multisites.ai/glossary/acclimatization)

## Sources

1.  [OSHA: Heat Overview](https://www.osha.gov/heat-exposure)
2.  [OSHA: Water. Rest. Shade.](https://www.osha.gov/heat-exposure/water-rest-shade)

![Ironworkers silhouetted on a steel frame against a hot orange sunset](https://jmarsolutions.multisites.ai/_astro/sunset-steel.IhAMDca0_6wk53.webp)

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