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Heat Index Calculator

🌡️Heat Index Calculator

Best for T > 27°C / 80°F

40–100%

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Detailed Guide Coming Soon

We're working on a comprehensive educational guide for the Heat Index Calculator in your language. The content below is shown in English.

이란 무엇인가 Heat Index Calculator?

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The heat index (also called apparent temperature or feels-like temperature in summer) estimates how hot it actually feels based on air temperature and relative humidity. High humidity prevents sweat from evaporating effectively, reducing the body's ability to cool itself. The Rothfusz (1990) regression equation used by NOAA and the NWS is the most widely accepted formula.

Calkulon makes complex calculations simple — built for students and everyday problem-solvers.

공식

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f(x)HI = −42.379 + 2.04901523T + 10.14333127R − 0.22475541TR

변수 설명

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기호이름단위설명
HI−42—−42

방법 Heat Index Calculator

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  1. 1Based on Rothfusz (1990) regression of physiological studies
  2. 2HI = −42.379 + 2.04901523T + 10.14333127R − 0.22475541TR ...
  3. 3T = air temperature (°F), R = relative humidity (%)
  4. 4Applies when T ≥ 80°F (27°C) and RH ≥ 40%
  5. 5Accuracy: ±1.3°F under typical conditions

풀어진 예시

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예제 1
주어진 값:35°C, 60% humidity
결과:Heat index ≈ 42°C — feels significantly hotter

Health risk threshold

예제 2
주어진 값:40°C, 80% humidity
결과:Heat index ≈ 60°C — extreme danger

Can be fatal without cooling

실제 적용

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Tracking personal health and fitness goals

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Guidance for healthcare conversations with your doctor

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Monitoring progress during a weight management programme

Heat Index Categories (NOAA)

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Feels-Like TemperatureCategoryHealth Effects
27–32°C (80–90°F)CautionFatigue with prolonged exposure
33–39°C (91–103°F)Extreme CautionPossible heat cramps/exhaustion
40–51°C (104–124°F)DangerHeat cramps/exhaustion likely; heat stroke possible
> 52°C (125°F)Extreme DangerHeat stroke highly likely

자주 묻는 질문

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Q

What is Heat Index Calc?

A

The heat index (also called apparent temperature or feels-like temperature in summer) estimates how hot it actually feels based on air temperature and relative humidity. High humidity prevents sweat from evaporating effectively, reducing the body's ability to cool itself

Q

How accurate is the Heat Index Calc calculator?

A

The calculator uses the standard published formula for heat index calc. Results are accurate to the precision of the inputs you provide. For financial, medical, or legal decisions, always verify with a qualified professional.

Q

What units does the Heat Index Calc calculator use?

A

This calculator works with inches, Celsius, Fahrenheit, percentages. You can enter values in the units shown — the calculator handles all conversions internally.

Q

What formula does the Heat Index Calc calculator use?

A

The core formula is: HI = −42.379 + 2.04901523T + 10.14333127R − 0.22475541TR . Each step in the calculation is shown so you can verify the result manually.

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전문가 팁

Heat index assumes shaded conditions. Direct sunlight can add an additional 8–15°C to the apparent temperature. Drink water before you feel thirsty — thirst indicates you are already mildly dehydrated.

Formula-verified for precision
Reviewed October 2026
Our methodology

Ratings & comments

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