Everyday Life calculator
Heat Index Calculator
Estimate apparent temperature from air temperature and relative humidity.
FormulaHeat index estimates apparent temperature from Fahrenheit 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.
FAQ6 common questions for this calculator.
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?+
For the Heat Index Calculator, 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?+
For the Heat Index Calculator, enter air temperature and relative humidity. Keep the units consistent with the calculator fields and compare your setup with the worked example on the page.
How accurate is the Heat Index Calculator?+
Heat Index Calculator is accurate for the values and assumptions entered on this page. It uses the Heat index approximation. Recheck the inputs before relying on the estimate.
What should I check before using the Heat Index Calculator result?+
For the Heat Index Calculator, check that the units, inputs, and assumptions match your situation. Change one input at a time to understand which values have the largest effect on the result.
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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.