Humidity & dew point converter
Enter the temperature and a known value for relative humidity, absolute humidity or dew point to convert between humidity, dew point and water vapor pressure. Supports °C and °F, and shows 4 values with units using the Magnus approximation over water. Copy all the results together or save them as TXT.
What you can do
Convert from the humidity value you know
Enter the temperature and whichever value you know: relative humidity, absolute humidity or dew point. All 3 input types are supported.
Check 4 measures together
View relative humidity, absolute humidity, dew point and water vapor pressure together in a list with units.
Supports Celsius and Fahrenheit
Choose °C or °F for temperature and dew point. Absolute humidity is shown in g/m³ and water vapor pressure in hPa.
How to use
Enter the temperature
Choose °C or °F and enter the temperature.
Choose the humidity value you know
Select the type of value you have from relative humidity, absolute humidity or dew point, then enter it.
Check the converted results
Press “Convert” and check the input conditions and all 4 measures. Copy or save all results together.
Useful when
Interpret temperature and humidity records
Use the temperature and relative humidity in a measurement record to check absolute humidity and water vapor pressure as well.
Compare dew point and temperature
Check the same air condition as a dew point temperature. You can also convert a known dew point to relative humidity at the specified temperature.
Humidity measures and calculation range
Relative humidity is a ratio; absolute humidity is an amount
Relative humidity is the ratio to the saturation water vapor pressure at that temperature. Absolute humidity is the mass of water vapor in 1m³ of air.
Dew point is the temperature at saturation
This is the temperature at which air reaches saturation when cooled while preserving water vapor pressure. It depends on both the temperature and the amount of water vapor present.
An approximation over water
Supports temperatures from −45 to 60°C (−49 to 140°F). Calculations use the Magnus approximation over water and do not include frost point over ice or corrections for measurement error.
Frequently asked questions
Can I convert at 0% humidity?
At 0% relative humidity, absolute humidity and water vapor pressure are 0. A finite dew point cannot be calculated, so an explanation is shown for the dew point.
Can I calculate relative humidity from the dew point?
Yes. Select “Dew point” as the known value, then enter the temperature and dew point. Conversion from absolute humidity is also supported.
Why is the dew point shown as out of range?
Even when the temperature is within the supported range, the calculated dew point may be below −45°C. In that case, no numerical dew point is shown, but you can still check the other measures.
Can I use conditions above 100% relative humidity?
This tool does not handle those conditions. If conversion from absolute humidity or dew point exceeds saturation, a message also asks you to check the input conditions.
Input and results
- Input
- Temperature and either relative humidity, absolute humidity or dew point.
- Results
- Approximate values for 4 measures. Changing the inputs or units clears the previous results.
- Save
- Copy all displayed results together or save them as TXT.