Calculate the dew point from air temperature and relative humidity, and see how humid it feels. Enter your values; the result updates as you type, with the method shown below.
About this calculator
The dew point is the temperature at which air becomes saturated and water condenses. It is a better guide to how muggy the air feels than relative humidity. This calculator uses the Magnus formula.
Enter the air temperature in °C and the relative humidity.
When to use it
- Judging comfort and mugginess.
- Preventing condensation and mould at home.
- Painting or varnishing outdoors.
- Weather and gardening.
How to read the result
22 °C at 60% humidity gives a dew point of about 13.9 °C (comfortable).
Below 10 °C feels dry, 10–16 °C comfortable, 16–21 °C humid, above 21 °C oppressive.
Mistakes to avoid
- Confusing dew point with air temperature.
- Painting when surfaces are near the dew point.
- Using it at very low humidity, where precision drops.
Formula
Magnus formula: Td = b·γ / (a − γ), γ = ln(RH) + a·T / (b + T)
Worked example
22 °C and 60% humidity: dew point 13.9 °C, comfortable.
Frequently asked questions
What is the dew point?
The temperature at which water vapour condenses.
Why is it useful?
It predicts condensation, mould risk and how muggy it feels.
Why is dew point better than humidity?
It does not change with air temperature during the day.
When does condensation form?
When a surface is colder than the dew point.
Can dew point exceed air temperature?
No.
Related calculators
- Wind Chill Calculator (Feels Like Temperature)
- Heat Index Calculator
- Voltage Drop Calculator
- Resistor Color Code Calculator
- Horsepower Calculator From Torque and RPM
- Molarity Calculator
- All calculators in this category
Results are estimates for information only. Check important figures with a professional.