How to Measure Humidity in an Incubator

Incubating chicken eggs is a delicate balance of temperature, humidity and ventilation. This occurs flawlessly under a hen. Humans incubating eggs manually must learn to maintain this balance. Too much or two little humidity during incubation can mean the difference between deformed chicks and those who die trying to hatch. There are three methods of measuring humidity during incubation: a wet-bulb thermometer, weighing or candling the eggs to determine the percentage of weight loss inside an egg and the use of a digital hygrometer. The latter, which requires little manipulation during the incubation, is likely the better choice for beginners.

Things You'll Need

Salt
Measuring cup
Cup or small bowl
Water
Large plastic bag
Digital hygrometer

Instructions

Calibrating the Digital Hygrometer
- 1
  
  Pour 1/2 cup of salt into a cup or small bowl. Add 1 cup of water and mix. The salt will not dissolve into the liquid.
- 2
  Insert the cup containing the salt mixture into a large plastic bag.
- 3
  Place the hygrometer in the bag. Do not allow the salt mixture to touch the hygrometer. This could damage the instrument. Seal the bag.
- 4
  Leave the bag undisturbed for 12 hours.
- 5
  Read the humidity on the hygrometer display without opening or moving the bag. It should read 75 percent humidity.
- 6
  Add or subtract the difference between the actual hygrometer reading and 75 percent to get the hygrometer's baseline reading.
Measuring Humidity During Incubation
- 7
  Place the properly calibrated hygrometer inside the incubator. It should be placed on the same level as the top of the eggs.
- 8
  Check humidity levels several times a day prior to turning the eggs.
- 9
  Maintain relative humidity levels inside the incubator at 50 to 55 percent for days one through 18. Increase humidity levels to 65 percent during the last three days of incubation.