It’s important to monitor the humidity levels in your home, as too much or too little can cause problems.
Luckily, there are several affordable DIY tools and methods that can be used to measure humidity levels in your home.
If you’re interested in finding out about ways to reduce humidity in your home without spending money on expensive measuring devices, read our article, “Lower Humidity in 14 Ways (With No Dehumidifier Required)“.
The dry and wet temperature test is the most accurate way to measure humidity without a hygrometer. It requires two thermometers: a wet and a dry thermometer.
A dry thermometer is a standard temperature-measuring device found at any hardware store. They are also pretty cheap, and you might have one already.
A wet thermometer is a thermometer with a muslin-covered bulb. To use it, soak the muslin in distilled water and wave it around in the target room. The evaporation process cools the bulb, which lowers the temperature readings.
After five minutes, check the temperature readings on both thermometers. These two measurements can be used to look up the relative humidity level on a Mollier Diagram or relative humidity lookup table.
The ice cube method is a simple test you can do with just an ice cube and a glass of water.
It’s not as accurate as the wet and dry bulb method, but you can do it with items you probably have lying around the house.
To use this method, fill a glass with ice cubes until it’s about three-quarters full. Then wait for about five minutes.
If there’s no visible condensation on the outside of the glass, the relative humidity in your home is low. If there is condensation, the relative humidity is high.
I have used this one personally, and while it isn’t the most accurate, it is quick, easy, and free!
Taking this approach means you might have to wait a few minutes for the ice cubes to melt and give you a reading, but unless you’re very impatient, that shouldn’t be a problem.
It may seem somewhat implausible at first, but you can make a hygrometer out of human hair.
Hair naturally expands and contracts in response to changes in humidity, so it makes a pretty good relative humidity sensor.
To make this DIY hygrometer, you’ll need a corkboard, some human hair, and a drinking straw or piece of card to make an arrow that will be used to indicate the relative humidity.
You also want to make a tiny hole that can fit a needle toward the bottom of the arrow. This hole should be loose enough to let the arrow move easily but tight enough so that it doesn’t fall out.
Tie one end of the hair to the end of the arrow and secure the other end to the corkboard. Make sure that the arrow is free to move up and down.
Take a blow dryer and point it at the hair for a few seconds. You should see the arrow move up. That’s your zero mark.
Then spray the hair with water (or place the hygrometer in a sealed plastic bag with a wet sponge) and see how far the pointer moves. That’s your 100% relative humidity mark.
You can use this hygrometer to measure the relative humidity in your home by checking where on the scale the arrow is.
This DIY hygrometer is very sensitive, so you may need to calibrate it by comparing it to a real hygrometer. But it’s a fun project and only requires things you probably already have around your house.
See the “how to” video below for a visual aid to construction.
Where to Buy a Hydrometer
If you’re not into science experiments, you can simply purchase a hydrometer at your local hardware store for around $15–20.
Your home humidity levels should be between 30 and 60%. Though, to combat mold growth, you might consider turning the levels down to around 50%.
Why Should You Monitor Humidity Levels?
Too much moisture in the air can cause problems around your home, such as mold and mildew growth. The high humidity levels can also cause wood trim and furniture to swell, rot, and warp.
Mold growth can bring a host of respiratory issues that can be especially damaging to those with asthma, allergies, or other lung conditions.
Too little moisture can cause wood trim to shrink, crack, and split. It can cause dry skin, dry eyes, static electricity, and increased susceptibility to cold and flu viruses.
While these fun humidity tests can give you a decently accurate reading, if you truly have a problem with your humidity levels (either too high or too low), you need to buy a hydrometer and see where your levels fall.
Professionally installed whole-home systems (for both humidifiers and dehumidifiers) will work best to regulate your home humidity levels but you can start by purchasing a portable unit from your local hardware store and see if it improves your levels.
If you have a large home, you may need to purchase more than one portable unit. Luckily, these aren’t too expensive and will go a long way toward maintaining the comfort of your home.