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Introducing Heat Strain Index, and Heat Strain Score

Our new metric, the Heat Strain Index and Score provides an easy and efficient way to assess the body's heat strain.


Jobs that involve working in extreme conditions, such as fire-fighting or mining, can have serious health implications due to thermal strain. It is crucial to have a convenient and straightforward measurement metric that can alert individuals when they reach hazardous heat strain levels.

Assessing Heat Strain

With simple and interpretable values, these metrics offer real-time and cumulative measurements of thermal strain, allowing individuals to monitor their heat stress levels effectively.

Heat strain is the physiological response of the body to heat stress, which requires additional resources to maintain a stable and healthy body temperature as the stress increases. Prolonged exposure to excessive heat can negatively impact cognitive and physical performance, posing risks to individuals and others during work-related activities or sports if not adequately monitored.

Research has shown that mean body temperature (MBT) is a reliable indicator for assessing heat strain. Our experts have conducted extensive laboratory testing and developed a formula that accurately estimates MBT using both core body temperature and skin temperature. Our non-invasive sensors can calculate two easily interpretable metrics that assess real-time thermal strain and continuous accumulated measurement.

The Heat Strain Index

The Heat Strain Index is a real-time measurement of the heat stress experienced by the body. It provides an easily interpretable score ranging from 0 to 10. A score of 10 indicates extremely high heat strain, corresponding to a skin temperature of 37 degrees Celsius and a core body temperature of 40 degrees Celsius. A score of 0 indicates that the thermoregulatory system is not under any stress, which can occur in cool working environments where skin temperatures are not elevated, allowing the body to dissipate heat easily.

The Heat Strain Score

In addition to the Heat Strain Index, we have developed the Heat Strain Score. This score offers a cumulative measurement of the heat strain experienced over a day. Scaled to a value of 1000, a score of 1000 represents exceptional heat exposure, with a Heat Strain Index of 10 sustained over an entire hour. The Heat Strain Score enables easy comparison of different periods to identify trends and patterns in the heat stress experienced by the body.

Accessing the Metrics

The Heat Strain Index (HSI) and Heat Strain Score (HSS) are readily available in our CORE app, and they will soon be integrated into our Calera app. Both apps are compatible with iOS and Android devices, ensuring accessibility for a wide range of users.

More Information

If you have any further questions about our product and index scores, we encourage you to contact our expert, David. He will provide a personalized explanation tailored to your specific inquiries. You can reach out to David via email: