How to Calibrate a Digital Hygrometer

A hygrometer.
  • 1 hours
  • Beginner
  • 60
What You'll Need
¼ cup water
½ cup salt
Re-sealable plastic bag
Digital hygrometer

A digital hygrometer is a useful tool that measures the relative humidity in a given area. The device usually comes in handy when storing cigars or other objects in a humidor. In order to keep the humidity in the humidor accurately constant, make sure to calibrate the digital hygrometer occasionally. Here are the instructions.

Step 1 - Mix the Salt Solution

In a porcelain, plastic, or metal cup, mix the salt and water. Stir the components together until all the salt particles are wet.

Step 2 - Seal the Mix and the Hygrometer

Place the cup into the plastic bag but be sure it sits on a stable flat surface. Place the hygrometer in the bag as well, but never allow it to get in contact with the mix inside the cup as this may damage the device. To ensure this does not happen, find a place where the set-up will not be disturbed by children or by any type of external force.

In addition, the set-up should be placed in an area with a constant room temperature. Inside a cabinet would work well. Just make sure that it is away from any source of heat such as direct sunlight, heating vents, ventilators, and the like. Seal the plastic bag when all the preparations are finished.

Step 3 - Read the Results

To ensure that the hygrometer reads the correct humidity inside the plastic bag, leave it for around 8 to 12 hours. After the waiting time, check the reading on the device while it is still inside the plastic bag. If the hygrometer is accurate, it should read 75 percent. Sometimes, it may read 3 percentage points above or below the normal reading (72 percent or 78 percent). In this case, continue with the calibration steps.

Step 4 - Calibrate the Device

Should the reading be below or above 75 percent, take the digital hygrometer out of the plastic bag quickly and simply press the calibration button. If you do not know where the calibration button is, make sure to check the specific location with the help of a user’s manual. If the device does not specify any calibration button, then find out where the reset button is. Press the reset button as soon as possible to ensure that the normal reading goes back to 75 percent.

What if There Is no Calibration Button?

Some digital hygrometers may not have calibration or reset button, but that is fine. Instead, subtract the value obtained from the device from 75 percent and take note of the difference. For example, if the result from the reading is 72 percent, then the difference is three. When reading the hygrometer in the future, add three to the resulting value to get the correct information. Before measuring the relative humidity in a humidor, make sure to allow the hygrometer to stabilize for about two hours.