Dew Point Calculator
Calculates dew point given air temperature in ℉ and % relative humidity.
Formula:((fcT=(fcTf-32)*5/9)+(fcC=ln(fcRH/100)+17.67*fcT/(243.5+fcT)))*0+(243.5*fcC/(17.67-fcC))*9/5+32
T ℉ (fcTf) = The temperature ℉
RH% (fcRH) = The relative Humidity %
Example 1
| Value | Keystrokes | Display | Description |
|---|---|---|---|
| 74 | T ℉ | 74.00 | Stores the temperature. |
| 50 | RH% | 50.00 | Stores the RH % |
| Tdp | 54.20 | Calculates the dew point. |
Example 2
Using the values in example 1, calculate the RH% for a dew point of 68 and a temperature of 74.
| Value | Keystrokes | Display | Description |
|---|---|---|---|
| 68 | Tdp | 68.00 | Stores the dew point |
| RH% | 81.55 | Solves for the RH% |
This calculator uses the Magnus formula in the referenced Wikipedia article with the NOAA constants.
These valuations provide a maximum error of 0.1%, for
-22℉ ≤ T ≤ +95℉;
1% < RH < 100%;
Reference: