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If you're a cigar aficionado, you need a hygrometer to make sure you're storing your wares at the correct humidity. A hygrometer is an instrument that is used to measure humidity in cigar humidors as well as greenhouses, incubators, museums, and more.[1] To ensure that your hygrometer is functioning properly, it is best to test it prior to use, then calibrate it if necessary. The salt method is a tried and true way of testing a hygrometer for accuracy. Here's how to do it.

  1. To test your hygrometer using salt, you just need a few household supplies:[2]
    • A small food storage bag that zips
    • A tiny cup or bottle cap from a 20-ounce soda
    • Some table salt
    • Water
  2. Don't add so much water that the salt dissolves; you just want it to be wet. If you add too much, use paper towels to mop up the excess.
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  3. Zip it up and place it somewhere out of the way, so it won't be disturbed during the test.[3]
  4. During this time the hygrometer will measure the humidity inside the bag.[4]
  5. If it's accurate, it should show a humidity of exactly 75 percent.[5]
  6. If your hygrometer shows a humidity lower or higher than 75 percent, you'll need to calibrate it so that it's accurate when you use it to check the humidity of your humidor.[6]
    • If you have an analog hygrometer, turn the knob to adjust it to 75 percent.
    • If you have a digital hygrometer, use the buttons to adjust it to 75 percent.
    • If you can't adjust your hygrometer, take note of how many percentage points higher or lower than 75 percent it is. Next time you use your hygrometer, add or subtract a few percentage points for an accurate reading.
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Community Q&A

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  • Question
    How do we know for sure the humidity is 75%?
    Community Answer
    Community Answer
    Salty solutions will create a specific atmosphere inside of the bag because of the modified vapor pressure. Just using distilled water, for example, would give you exactly 100% RH, and a saturated lithium chloride solution would give you about 11% RH. Keep in mind that this is true only at room temperature (20 °C), the whole process is temperature-dependent. Table salt (sodium chloride) tends to be very stable in that regard (less than 1 % change between 0 °C and 30 °C).
  • Question
    I calibrated my hygrometer for 30 hours and it read 74%. I adjusted it to 75%, but after 24 hours in my humidor, it read 66%. Is it broken or did I do something wrong?
    Community Answer
    Community Answer
    It doesn't sound like it's broken. More likely is that the humidor is dry.
  • Question
    I have 2 hygrometers. One shows the room at 25%, and the other shows it at 40%. In the salt test, using the same container, the first goes to 80% and the second goes to 75%. What explains this?
    Community Answer
    Community Answer
    It tells you that second hygrometer is accurate and your room is at 40% relative humidity. It also tells you need to calibrate the first one.
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Tips

  • Use the same Salt Test method using any of the following: Lithium Chloride, Magnesium Chloride, Potassium Carbonate, Potassium Sulfate. The readings for these should be 11%; 33%; 43%; and 97% respectively.
  • Some hygrometers are known to have fluctuations in accuracy over time. It is best to test a hygrometer every 6 months to maintain accurate readings.
  • The humidity in your humidor should be kept between 68 and 72 percent to keep your cigars fresh.
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Things You'll Need

  • Hygrometer
  • Screw-on bottle cap
  • Salt
  • Water
  • Sealable plastic bag

About This Article

wikiHow is a “wiki,” similar to Wikipedia, which means that many of our articles are co-written by multiple authors. To create this article, 12 people, some anonymous, worked to edit and improve it over time. This article has been viewed 191,507 times.
24 votes - 96%
Co-authors: 12
Updated: October 9, 2024
Views: 191,507
Categories: Meteorology
Thanks to all authors for creating a page that has been read 191,507 times.

Reader Success Stories

  • Marc Levine

    Marc Levine

    Sep 25, 2017

    "I have a nice size cigar collection and very top shelf. I need an accurate hygrometer reading to protect my..." more
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