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Dew Point Calculator

Calculate dew point and absolute humidity from temperature and relative humidity.

Last updated · View algorithm, constants and default inputs (JSON)

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Dew point 13.9°C
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Dew point (°C)

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Dew point (°C)Dew point (°C): 13.88; Air temperature (°C): 22.00 / Air temperature (°C): 16.50; Dew point (°C): 8.70 / Air temperature (°C): 17.88; Dew point (°C): 10.00 / Air temperature (°C): 19.25; Dew point (°C): 11.29 / Air temperature (°C): 20.63; Dew point (°C): 12.58 / Air temperature (°C): 22.00; Dew point (°C): 13.88 / Air temperature (°C): 23.38; Dew point (°C): 15.17 / Air temperature (°C): 24.75; Dew point (°C): 16.46 / Air temperature (°C): 26.13; Dew point (°C): 17.75 / Air temperature (°C): 27.50; Dew point (°C): 19.04Dew point (°C)7.711.815.920.116.522.027.5Air temperature (°C)Dew point (°C): 13.88 (22.00)

About this calculator

Dew point is the temperature at which air would reach saturation if cooled at its current water-vapor content. Relative humidity usually falls as air warms without added moisture, while dew point is more stable in that specific situation; mixing, evaporation or condensation can change moisture. This near-surface estimate uses a Magnus approximation for −45 to 60 °C (−49 to 140 °F), assumes typical surface pressure and does not adjust for station pressure. Comfort bands are rough guides.

Worked example

calculated with the default values below

Air temperature 22 °C · Relative humidity 60 % · Temperature unit Celsius Dew point 13.9 °C · Dew point 57.0 °F · Frost point (if below freezing) 12.1 °C · Absolute humidity 11.62 g/m³ · Vapour pressure 15.82 hPa · Comfort level Pleasant · Temperature minus dew point 8.1 °C

General background references

Disclaimer

These calculators give general estimates. Sizing, pricing, availability and standards vary by brand, retailer and country, so treat the output as a starting point and confirm it against the seller's or authority's own figures.

Maintained by: CalcDelta

Implementation source

This record describes the implementation used by this page. It is not independent validation. External references, when available, support only the stated formula or definition; estimates and custom rules retain their own assumptions.

View algorithm, constants and default inputs (JSON)

Formula and variables

e = 6.112 × exp(17.62T ÷ (243.12 + T)) × RH ÷ 100; T_d = 243.12 ln(e ÷ 6.112) ÷ (17.62 − ln(e ÷ 6.112)); T_f = 272.62 ln(e ÷ 6.112) ÷ (22.46 − ln(e ÷ 6.112))

T
Air temperature (°C)
RH
Relative humidity (%)
α
Magnus term
T_d
Dew point (°C)
e
Vapor pressure (hPa)
AH
Absolute humidity (g/m³)

T is in °C; Fahrenheit input is converted first. T_d is dew point over water and T_f is frost point over ice. Absolute humidity = 216.7e ÷ (T + 273.15) g/m³. Near-surface estimate; pressure enhancement is omitted. Formula approximation shown for −45 to 60 °C.

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Frequently asked questions

Does dew point always stay constant when air warms?

No. Dew point is more stable when air warms without gaining or losing moisture, because relative humidity usually falls as saturation vapor pressure rises. Mixing with other air, evaporation and condensation can change the water-vapor content and therefore the dew point. The comfort labels are rough guides.