calibrate humidity gauge


Staff member
New Jersey
I have about five humidity meters in my house (analog), and a few read about the same, and a few are fairly far off. I dont necessarily trust any of them. Any recommendations on how to best calibrate them? Id imagine that even a digital meter would stray from calibration and should be considered to need calibration from time to time?
Southeastern, PA
We had a Vaisala humidity meter at work years ago that I would calibrate. Calibration involved two containers, each partially filled with a different saturated salt solution. You had to let the containers stabilize for a day. Then you placed the probe in the atmosphere above the salt solution (it was a special container designed for the probe to minimize "contamination" with room air). The saturated salt solution provided a known humidity (adjusted for temperature). One type of salt provided a relatively high humidity to calibrate to and the other salt provided a relatively low humidity. I know this probably won't help you, just some information on how humidity probes can be calibrated.