DewPtCm

This app computes the dew point temperature and relative humidity from an input wet bulb temperature, dry bulb temperature and barometric pressure. If a barometer is not available a guess of 760 mm of mercury will usually give a near enough result. Temperatures are in degrees Celsius and barometric pressure is in mm of mercury.
No need for internet access.
Uses a computation method published by the National Weather Service of the National Oceanic and Atmospheric Administration, USA.