μg/kg
microgram per kilogram of dry air
Humidity ratioexact by definition
The microgram per kilogram of dry air is 10⁻⁹ kg/kg, one part per billion by mass. Semiconductor and analytical process gases are specified here, where a −80 °C dew point corresponds to roughly 340 μg/kg.
| 1 μg/kg | 0.000001 g/kg |
Solvers that use humidity ratio