It is a good idea, but has to be calibrated, it is not self calibrating, then the battery went to 25% for a bit more than 2 months and started giving crazy readings. Good that I have another hygrometer and number of 69% packs, which take the excess humidity if such, so was relatively sure what the humidity is and that the reading of this one is bad, else might have taken wrong actions. Now need to change battery and recalibrate for another couple of months work... does not worth the effort just to have readings on the phone... my other hygrometer is the round Xikar, 6 years old, works 2 years with one battery, no special needs and very punctual.
