Everyday Life calculator
Heat Index Calculator
Estimate apparent temperature from air temperature and relative humidity.
Formula
Heat index approximation
This is a weather comfort estimate. Follow local weather service warnings for safety decisions.
Heat index estimates apparent temperature from Fahrenheit temperature and relative humidity
High humidity can make 92 F feel much hotter.
FAQs
Why does humidity matter?+
High humidity slows evaporative cooling from skin.
What units does it use?+
Enter temperature in Fahrenheit and humidity as a percentage.
How does the Heat Index Calculator calculate the result?+
It uses the Heat index approximation: Heat index estimates apparent temperature from Fahrenheit temperature and relative humidity. High humidity can make 92 F feel much hotter.
What information do I need to use the Heat Index Calculator?+
Estimate apparent temperature from air temperature and relative humidity.
How accurate is the Heat Index Calculator?+
Heat Index Calculator applies the formula and assumptions shown on this page. Results may be rounded for readability, so verify changing rates, thresholds, medical guidance, or legal rules with the cited source or a qualified professional.
What should I check before using the Heat Index Calculator result?+
Check that the units, dates, rates, and assumptions match your situation. Change one input at a time to understand which values have the largest effect on the result.
Everyday Life guide
How to use the Heat Index Calculator
Estimate apparent temperature from air temperature and relative humidity. The page also explains the heat index approximation and shows a practical example: High humidity can make 92 F feel much hotter.
- 1
Enter your details
Enter air temperature and relative humidity, then complete any other fields shown in the calculator.
- 2
Check the calculation
Review the result alongside the heat index approximation: Heat index estimates apparent temperature from Fahrenheit temperature and relative humidity.
- 3
Compare scenarios
Change one or more inputs to see how they affect the heat Index Calculator result before you use the estimate.
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