# Heat Index Calculator

The perceived heat, the heat index, can be calculated from real temperature and humidity. This is a subjective value for the perception of heat above about 20°C. The greater the humidity, the greater the perceived heat. Humidity can be measured with a hygrometer. The wind speed does not play a role for warm felt temperature, but it does for cold, for this see windchill. A heat index from around 40°C is considered dangerous; in extreme cases, values of over 70°C can occur in nature.

Please enter the real temperature and humidity, the heat index will be calculated.

The formula for the calculation is h = -8.784695 + 1.61139411*t + 2.338549*f - 0.14611605*t*f - 0.012308094*t² - 0.016424828*f² + 0.002211732*t²*f + 0.00072546*t*f² - 0.000003582*t²*f²

h = heat index in degrees Celsius , t = real temperature in degrees Celsius, f = humidity in percent

Example: at 30 degrees Celsius and 80 percent humidity, the heat index is almost 38 degrees Celsius.

Physics commonly uses SI units. Here is a calculator to convert lengths, temperature, pressure, speed and other units.