The One-Step Calibration Kit is a simple and surefire method to accurately calibrate any digital or analog hygrometer or humidity sensor.
The One-Step Calibration Kit utilizes Boveda's 75.5% or 32% relative humidity standard, which is widely used and accepted by chemists and lab professionals to determine the accuracy of any hygrometer (also known as the "salt test").
Simply place your hygrometer inside the bag, close the zipper, and wait 24 hours. A perfectly-calibrated hygrometer will read 75% or 32% RH (depending on the calibration kit you buy). If your hygrometer reads above or below that number, adjust the calibration by the number of percentage points it is off from 75% or 32%. Then place the hygrometer back in the bag to check that the adjustment worked.
For even more accuracy, you can buy both RH levels and perform a two-point calibration. Perform the calibration steps in one bag, then move the hygrometer to the other bag and perform another calibration.
Note: Do not mix Boveda RH levels within the same humidor, and do not use Boveda in the same humidor with other humidification products. They will fight against each other and reduce the efficiency of the Boveda.