Heat Stress Risk Calculator
Enter the conditions and the type of work, and get a heat stress risk rating with rest and water guidance for outdoor crews. Built on the Safe Work Australia approach to managing heat and the WBGT thresholds that Australian guidance draws on.
Aligned with the Safe Work Australia risk management approachEstimated WBGT 27.0°C. At moderate work, that sits in the Moderate band.
Work and rest
Work at a steady pace. Take a short break in shade each hour and ease off if anyone is struggling.
Water
Drink cool water in small amounts often, about a cup every 20 minutes. Do not wait until you feel thirsty.
Controls to set up
Provide shade and cool water on site. Keep an eye on each other and rotate the heavier tasks.
Watch for
Headache, dizziness, cramps, nausea or heavy sweating that suddenly stops. Confusion or collapse is an emergency: call 000, cool the person fast.
Read this before you rely on it
This is a screening estimate to support planning and conversations on site. It is not a measured WBGT reading, and it does not replace a workplace risk assessment, a WBGT meter, or advice from an occupational hygienist. Risk varies from person to person with age, fitness, health conditions, pregnancy, medications, hydration, and the clothing or PPE worn. Safe Work Australia does not set a single legal temperature to stop work. A business still has a duty to manage the risk so far as is reasonably practicable. Check the Bureau of Meteorology for current local conditions.
▸ How the rating is worked out
Wet Bulb Globe Temperature (WBGT) is the index most heat guidance uses, because it reflects how hard the body works to stay cool, not just the air temperature. This tool estimates WBGT from the temperature and humidity you enter using the Australian Bureau of Meteorology approximation, then adds an allowance for sun exposure. That estimate is compared against work and rest thresholds that get stricter as the work gets heavier, and stricter again for workers who are not used to the heat, following the approach in ISO 7243 and the ACGIH threshold limit values that Australian guidance is based on. Heavier work produces more body heat, so the safe limit sits lower. A true site reading from a calibrated WBGT meter will always be more accurate than an estimate.
Where a cooling fan fits
Safe Work Australia lists air movement and fans among the engineering controls for working in heat. A personal fan moves air across the body and helps sweat evaporate, which aids comfort during work and speeds cooling on a break. It is a personal fan, not an air conditioner, and it does not replace water, shade, rest, or moving heavy work to a cooler part of the day. Used alongside those, hands-free cooling is one practical option for crews who cannot get out of the heat.