How to Calibrate your Hygrometer

A hygrometer is an instrument used to measure relative humidity, over time your hygrometer will become inaccurate and need calibrating. I suggest calibrating at least once a year to ensure your hygrometer is also accurate.

To calibrate your hygrometer you need a coffee cup, half a cup of table salt, a quarter cup of water, hygrometer and a large resealable freezer bag.

• Firstly place half a cup of salt in the coffee cup and add a quarter cup of water, then stir to saturate the salt, the consistency should end up like wet sand.
• Place the coffee cup and hygrometer in the freezer bag but away from each other make sure none of the water touches the hygrometer as this could damage it.
• Seal the bag.
• Place the bag at room temperature for 8-12 hours at room temperature. Make sure it is away from any drafts, direct sunlight heating or cooling vents. The temperature needs to be fairly constant.

After 8-12 hours check the hygrometer while its still inside the bag, it should read 75% as the salt water provides 75% humidity. If you hygrometer reads 75% then great its all set if not then you can adjust it by turning the little screw in the back, i would then suggest repeating the process to ensure accuracy. If you have a digital hygrometer press the reset button, this will put the hygrometer at 75% and again i would suggest to repeat the process to ensure accuracy.

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Written by Oliver Partington - 06/02/2020