Hygrometers can be calibrated using saturated and unsaturated salts from ranges 11-90%. The effect of temperature on humidity measurement is very important and will always be included on the calibration certificate.
For humidity calibration, we require the fixed humidity points (normally 11,33,54,75 and 90%) in order for us to perform calibration. These are typically according to the working range/s it’s used at.
TriLab Support offers calibration via a reference humidity meter. Alternatively, precision reference standards are used.