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Calcimator

Heat Index Calculator

Calculate the heat index (feels-like temperature) based on air temperature and humidity. Assess heat danger level.

Inputs

°F
%

Results

Heat Index

113.1°F

Heat Index235.72°F
Feels Like Increase18.1°F
Danger LevelDanger — heat cramps/exhaustion likely
How to Use This Calculator
  1. Enter the Air Temperature in °F (the calculator applies the NOAA heat index formula when temp is 80°F or above).
  2. Set the Relative Humidity (%).
  3. Review the Heat Index in °F and °C, the Feels Like Increase above actual temperature, and the Danger Level.
  4. At Extreme Danger (130°F+), limit all outdoor exposure and seek air conditioning immediately.

How the result changes with Temperature

TemperatureHeat Index
5957.4°F
8284.4°F
109166.5°F
131297.8°F

What each input means

Temperature
Temperature in the selected unit.
Relative Humidity
Relative humidity as a percentage.

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    Temperature = 95, Relative Humidity = 60 = 2 input(s) provided
  2. Calculate Heat Index
    Heat Index = hi
    113.1 = 113.1
  3. Calculate Heat Index
    45.1 = 45.1
  4. Calculate Feels Like Increase
    Feels Like Increase = round((hi - tempF) * 10) / 10
    18.1 = 18.1

Engine last updated . Checked against 2 independently-derived tests — how we verify calculators.

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