Enter the conditions you will be working in. The calculator returns how hot your body will get, how much water you will lose, and how long you can keep going before you must stop.
Results
About this calculator
The model treats the body as two compartments, core and skin, and integrates the heat balance equations forward in time at one-minute steps. At each step it computes the heat balance across the skin surface, the maximum sweat rate the body can produce, the maximum evaporation the environment can absorb, and the resulting change in body temperature.
Three exposure limits are returned. Rectal temperature limit is 38°C. Water loss limits correspond to 5 per cent of body mass for 95 per cent of workers (Dmax95) and 7.5 per cent for the average worker (Dmax50). The earliest of these three is the maximum allowable exposure time for the conditions entered.
The model is validated for metabolic rates up to approximately 450 W/m². Above that, sweat rate saturation in the model means results understate the strain and should be treated as illustrative only.
Standard. ISO 7933 (current edition 2023, prior edition 2018). Reference computation values are given in Annex F of the standard.
Citation. Malchaire J, Piette A, Kampmann B, Mehnert P, Gebhardt H, Havenith G, den Hartog E, Holmer I, Parsons K, Alfano G, Griefahn B. Development and validation of the predicted heat strain model. Annals of Occupational Hygiene 45(2):123-135 (2001). BIOMED2 European Union project, 1996 to 1999.