Dew Point Calculator
The humidity figure that actually predicts comfort.
Work out Dew Point. The humidity figure that actually predicts comfort. Names the misconception directly.
Dew point
21.4 °C
70.5 °F · Severely oppressive — heat stress risk
Dew point measures how much moisture the air actually holds, which is why it predicts comfort far better than relative humidity does. 90% humidity at 5 °C is pleasant and 60% at 30 °C is oppressive — the dew points, about 3 °C and 21 °C, say so immediately where the humidity figures mislead completely. As a rough guide: below 13 °C feels pleasant, 16 °C is noticeably humid, above 21 °C is oppressive to almost everyone. The spread between air temperature and dew point predicts fog and cloud base. As the spread closes towards zero the air is saturated, which is why fog forms on clear still nights when the ground cools the air down to its dew point.
How the Dew Point Calculator works
Enter temperature and relative humidity for the dew point, the spread and how it will feel. Dew point measures absolute moisture, which is why it predicts comfort far better than relative humidity does.
Also known as: relative humidity to dew point · dew point comfort chart · when will fog form · dew point formula
Frequently asked questions
What is dew point?
The temperature air must cool to before its moisture condenses. It measures how much water the air actually holds, rather than how close it is to full at the current temperature.
Why is dew point better than humidity for comfort?
Because relative humidity is relative to temperature. 90% at 5 °C is pleasant and 60% at 30 °C is oppressive — the dew points, roughly 3 °C and 21 °C, tell you that instantly where the humidity figures mislead.
What dew point feels comfortable?
Below about 13 °C feels pleasant to most people, 16 °C is noticeably humid, and above 21 °C is oppressive to almost everyone. The scale is remarkably consistent across climates.
When does fog form?
When air cools to its dew point, so the spread between temperature and dew point closes to nothing. A small spread on a clear still night is the classic fog setup, as the ground radiates heat away and chills the air above it.
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