Heat Index (HI) Calculator

Heat Index (HI) Calculator

°F

%

Heat Index (HI) Calculator Results
 Fahrenheit (°F)Celsius (°C)Kelvin (K)
Heat Index (HI):---
Heat Index Chart (Apparent Temperature)
Temperature (°F)Relative Humidity (%)
404550556065707580859095100
110136143152161171182194206219233247262278
108130137144153162172182193205218231245260
106124130137145153162172182193204216229243
104119124131137145153161171181191202214226
102114119124130137144152160169179189199210
100109114118124129136143150158167176185195
98105109113117123128134141148156164172181
96101104108112116121126132138145152160168
9497100102106110114119124129135141148155
92949699101105108112116121126131137143
9091939597100103106109113117122127132
88888991939598100103106110113117121
868587888991939597100102105108112
848384858688899092949698100103
8281828384848586888990919395
8080808181828283848485868687
Classification:Very WarmHotVery HotExtremely Hot

How the Heat Index (HI) Calculator can help you

Heat Index (HI) Calculator will help you calculate the heat index (HI) based on air temperature (T) and relative humidity (RH).

How to use the Heat Index (HI) Calculator

1. Select the “Temperature Units” from drop-down list;

2. Enter the “Air Temperature”;

3. Enter the “Relative Humidity”;

4. Click on the “Calculate” button to get the results.

Heat Index (HI) Calculator

HI (Heat Index, °F) = C1 + C2 T + C3 RH + C4 T RH + C5 T2 + C6 RH2 + C7 T2 RH + C8 T RH2 + C9 T2 RH2 + CF

HI means the heat index (°F);

T means the air temperature in Fahrenheit (°F);

RH means the relative humidity (%);

CF means the correction factor;

C1 = -42.379;

C2 = 2.04901523;

C3 = 10.14333127;

C4 = -0.22475541;

C5 = -6.83783 × 10 -3;

C6 = -5.481717 × 10 -2;

C7 = 1.22874 × 10 -3;

C8 = 8.5282 × 10 -4;

C9 = -1.99 × 10 -6.

If 80°F ≤ T ≤ 112°F, RH ≤ 13%; CF (Correction Factor) = – ([13 – RH] / 4) × ([17 – |T – 95|] / 17)0.5

If 80°F ≤ T ≤ 87°F, RH > 85%; CF (Correction Factor) = 0.02 × (RH – 85) × (87 – T)