Work out relative humidity from dew point instantly with clear inputs, formula shown and shareable results.
Dew point is the temperature at which the air's existing moisture would saturate, so the actual vapour pressure equals the saturation pressure at the dew point. Relative humidity is that value as a percentage of saturation at the real air temperature, computed here with the Magnus-Tetens expression. Air at 30 C with a 20 C dew point sits near 55% relative humidity.
Magnus saturation pressure
es(T) = 6.112 x exp(17.62T / (243.12 + T)) hPa
Relative humidity
RH = 100 x es(dew point) / es(air temperature)
No - it would mean supersaturation. If entered that way the calculator clamps the dew point to the air temperature, giving 100%.
Because it tracks the absolute moisture content. A 24 C dew point feels oppressive whatever the relative humidity reads.