Dew Point, Heat Index & Wet-Bulb Calculator

Enter air temperature and relative humidity — the tool computes the dew point (Magnus formula), heat index (NOAA Rothfusz), wet-bulb temperature (Stull), absolute humidity, and a comfort rating. Supports Celsius and Fahrenheit.

Interpretation guide

Dew point < 13°C (55°F)Dry, comfortable

13–18°C (55–65°F)Pleasant to slightly sticky

18–21°C (65–70°F)Sticky, uncomfortable

> 21°C (70°F)Oppressive, tropical

Heat index 27–32°CCaution — fatigue possible

32–41°CExtreme caution — heat cramps

41–54°CDanger — heat exhaustion

> 54°CExtreme danger — heatstroke imminent

Formulas used:
• Dew point: Magnus-Tetens — α = ln(RH/100) + (a·T)/(b+T), Td = (b·α)/(a-α) with a = 17.625, b = 243.04
• Heat index: NOAA Rothfusz regression (valid for T ≥ 80°F and RH ≥ 40%), with Steadman fallback below.
• Wet-bulb: Stull (2011) empirical — ±0.3°C accuracy for 5–99% RH and -20–50°C.
• Absolute humidity: AH = (6.112 · e^((17.67·T)/(T+243.5)) · RH · 2.1674) / (273.15 + T) in g/m³.

💧 Dew Point & Heat Index Calculator

Inputs

Interpretation guide