Homemade Psychrometer

4.3 based on 18 ratings

Updated on Aug 02, 2013

When you walk outside on a humid summer day, you can practically feel the moisture hanging in the air. But how can you measure humidity? Believe it or not, you can make your own instrument, called a psychrometer, to measure the humidity in the air.


How can I measure humidity?


  • Gauze
  • 2 thermometers
  • Rubber band
  • Glass jar
  • Water
  • Tape


  1. Wrap a strip of gauze around the base of the first thermometer several times.
  2. Wrap a rubber band around the gauze to keep it in place.
  3. Fill the jar with several inches of water.
  4. Put the wrapped thermometer into the jar, making sure that the bulb is under the water.
  5. Tape the second thermometer to the outside of the jar.
  6. Leave the psychrometer outside for at least 15 minutes.
  7. Write down the time, as well as the readings on the two thermometers in a table, such as the one below.

Fill in the last column of the table by subtracting the lower reading from the higher reading. This last column will correspond to the humidity in the air. A higher number in this column means that there is less humidity in the air, and a lower number in this column means that there is more humidity in the air.

Keren Perles has worked as an educational writer, editor, teacher, and tutor of all ages. Her experience spans the subject areas, from science and math, to English and the Hebrew language.

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