Calibrating Your Hygrometer

No matter how often I fill my humidification device, my hygrometer reads 60 percent relative humidity. I suspect that it's off, but I'd like to know by how much. How do I calibrate my hygrometer?

First, the best test for a cigar's humidity is feel.

Pick up the cigar and examine it. If it feels well humidified, it probably is. If you simply must know your hygrometer's margin of error, follow these steps: If you have an analog hygrometer (the kind with a needle and a dial), place it into a moist towel. Take it out after 15 minutes. It should read between 98 and 100 percent. Whatever the difference from this range, add or subtract that to all readings in the future.

In other words, if it reads 90 percent, add eight to 10 percentage points to whatever your hygrometer reads after you return it to your humidor. Most analog hygrometers also have a hole in the back that allows you to adjust the settings to the margin of error.

If you have a digital hygrometer, use the same technique. The only difference is that few digital units allow you to re-calibrate the settings. Most are well-made, though, so you probably won't need to.

Christopher Mitchell August 25, 2011 11:23pm ET
Think the sentence should be changed to "No matter how often I fill my humidifier my hygrometer reads 60 percent relative humidity", unless we are talking about filling the digital hygrometer with batteries.
Kirk Peurrung Seal Beach, CA, USA, September 18, 2011 3:39pm ET
If you re-read the original sentence you will see that it is correct. "Humidification device" and "humidifier" are synonymous.
Alex Sundstrom Ranson, wv, USA, March 27, 2015 1:08pm ET
Very good advice on calibrating the hydrometer. I could tell by sight and feel that my cigars were in good shape but hydrometer always gave a reading that the humidity level was low. I did as you instructed and found my hydrometer was about 15 points off. I adjusted it and now it confirms the humidity level is right on.

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