How to Calibrate a Hygrometer

time2012/04/17

A hygrometer is an instrument used to measure relative humidity. Relative humidity is a measure of how much water the air is holding, relative to the maximum amount of water the air could possibly hold at a given temperature.


Because of the delicate design of hygrometer it is easy for them to become innacurate (e.g. with shipping or just over time). A simple method of calibrating your hygrometer will help ensure you are measuring the relative humidity as accurately as possible.Hygrometer should be calibrated yearly.

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Hygrometers are available in both digital and dial models, and both should be checked for calibration. Some dial types will have a small screw or adjusment on the back so you can adjust them after calibration. If there is no way to adjust them, make a note of the calibration result, and then you can simply add or subtract from the actual reading to get a more accurate humidity level (this is discussed in greater detail after the calibration process is explained).

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Tip: give a hygrometer about 2 hours to stabilize before taking a reading, as changes in the relative humidity may take a while to register accurately on a hygrometer.