How (in)accurate can a hygrometer be?
After struggling with humidity issues in New England winters, I added a whole house humidifier when I replaced my A/C. That device claims 40, my portable in-room auto-humidifier claims 55, and the cheapo Amazon 6-pack hygrometer I leave inside my guitar case or near my guitar stands claims 36.
I don’t know how inaccurate they can be. I do know the humidity is different in different parts of my house. The inexpensive hygrometers I bought are able to be (and needed to be) calibrated. I purchased Boveda one-step calibration kit and adjusted accordingly. Maybe calibrate your smaller ones and use them as a comparison for the others?
I’ve seen digital hygrometers out by as much as 35%. The one on my humidifier says it’s 23% and my two calibratec analog hygromiter both say 48%. If I believed the digital one on my humidifier I’d have water running down my walls if i set it to 45.
So if you want to know what your guitar room real is get a analog hygrometer and calibrate it. You can buy a calibration kit(most accurate)or do a salt test to calculate it.
Interesting. I have a Govee hygrometer in the music room that seems fairly accurate. The humidifier in that room doesn’t say what the humidity is but it will kick off when the target humidity is reached. And it’s within a couple % of the Govee one.
I got a “smart” zigbee temp/humidity sensor in here, too, and it’s currently within 1% humidity of the Govee sensor.
My humidifier has a hard time getting the room up to 55% humidity when the ambient humidity is low (mostly just happens when it’s cold outside). I think I’m on a trajectory to get my own whole home humidifier. But unfortunately, I’ll probably wind up doing the entire HVAC in my house at the same time because the builders apparently did the whole thing wrong and the inspector missed it when I bought the place (because the builders were sneaky and hid the evidence).
For now, I think I’m going to wind up with a second room humidifier. This time instead of it trying to reach a “target” humidity on its own, I’m going to buy a “dumb” one and use a smart plug to have my smart home system automate that one. With the two running together, I ought to have no trouble keeping the humidity where it needs to be.
The same humidifier can have different reading when moved just a few feet in the same room. If it matters, make your own calibration kit and calibrate one or two humidistats. Use those to compare to others.
It looks like Bovida only makes a 75% calibration kit and that is useless for the humidity range we like for guitars. Your humidistat is likely to still be way off at 40% even when calibrated to 75%. They used to make a 20 or 30% one.
Hi Ashu ,
Due to a hobby that got out of hand about 6 years ago, I bought some of the same meters as that black little one…I bought 18 or so after a tip and threw away 7 or so because they were extremely deviating measurements… …they are not the best quality 
And of course you have to check every digital meter…
Greetings
Thanks for the tips everyone. I will look into calibration, analog meters etc.
Darn, no more Boveda 32% calibration kits!
@Beatup6String Ashu, here’s an article I found in Acoustic Guitar Forum on calibrating hygrometers using lab-grade potassium carbonate. In case you can’t access the article on the forum, here’s a direct link to the same article on the guy’s website.
