How accurate is my hygrometer?

If it is an analog (dial-type) hygrometer, it’s next to useless. If you care anything about your cigars, you should own a good digital hygrometer. Most digital hygrometers are accurate to +/-5-7% RH, which means the 70% reading on your display could translate to 65% to 75% in actual humidity in your humidor. Even if the manufacturer specifies your humidor is accurate to +/-5%, it doesn’t tell you the calibration of your particular hygrometer. A difference of 5% will make a big difference to your cigars, so you should calibrate your hygrometer annually.