We designed our sensors to measure in groups, so they are calibrated in groups.
This is done to minimize the differences between the individual sensors, so that all differences you see are real differences!

We are using environmental-friendly
salt & water solutions, that are known to give best results in accuracy-calibration.

We calibrate at four measurement-points between 11% and 98% rel. humidity. In this way we get for every sensor individual calibration-parameters, which will be programmed together with the calibration-date into the NVRAM of the sensor. Later the  DataServer will be able  to calculate with this information the humidity with a tolerance of less than +-1.8% rel. hum..