How To Measure Humidity Indoors? (With and Without a Hygrometer)

Nobody likes an extra humid home.

Humidity can cause you to sweat, bog you down, and take away your energy (and let’s not even talk about what it can do to your hair or makeup), so it’s important to know how much humidity is in the air.

But what does this mean? What exactly is humidity, and what makes it so awful?

In a nutshell, humidity refers to the amount of moisture in the air.

This moisture can be collected from the surrounding environment (including rooms in your house) to create humid and muggy atmospheres that can make you feel downright awful.

With all this being said, how do you know how much humidity is in the air?

How to Measure Humidity

As it turns out, there are several ways you can measure it.

Hygrometers (humidity-measuring tools) are the most common way, but there are many other hygrometer-free ways you can measure the humidity of your home if you don’t have one handy.

In this guide, we’ll go over exactly how you can use a hygrometer to check humidity levels in your house and also cover some other ways you can see if your home is too humid.

By following the information in this guide, you’ll be able to take the first step to make your home less humid!

How to Measure Humidity with A Hygrometer?

So, you’ve just purchased your hygrometer, but you’re not quite sure how to use it.

No worries!

Successfully using your device for an accurate humidity reading is simpler than you may think.

For starters, you’ll want to make sure that you are choosing the right location.

This means, in general, that you choose a room that doesn’t experience vast temperature or humidity fluctuations, as this can throw off your reading and give you inaccurate data.

Knowing this, it’s best to start in a room that’s not overly damp, such as your kitchen or bathroom; to be safe, you always want to use a room that’s not widely accessed, such as a family room where everyone is gathered.

Following these guidelines, you simply need to put your hygrometer in the room and leave it for a few hours.

You want to give the device time to read the humidity levels over a good enough time span so that you can get a more accurate idea of what’s going on in your air.

Checking on your hygrometric reading every few minutes will only throw off your data, so be sure to give it at least five hours before checking back in.

There are also other guidelines that you should keep in mind.

To begin with, you want to make sure that you’re not placing your hygrometer near dehumidifiers, air conditioners, heaters, or doorways, as locations such as these can experience wild fluctuations in temperature that will give you an inaccurate reading.

Keeping the temperature constant is key, as your humidity rating is dependent on the specific temperature in your room.

For this reason, you’ll also want to be sure not to touch the thermostat while you’re getting your reading.

Your hygrometer will give you a reading on a scale of zero to one hundred. Higher numbers mean more humidity, and lower numbers mean increased dryness.

Remember that your reading is giving you a humidity relative to the specific temperature, so higher numbers always mean that your room is too humid.

How to Measure Humidity without A Hygrometer?

But what should you do if you do not own a hygrometer?

Never to fear—there are several fantastic ways to see if your home is too humid.

Many of these methods require no expensive tools or equipment and are things you can easily at your house with little preparation.

So, let’s dive in and see what you can do to measure humidity in your house without a hygrometer.

The Ice Trick (Part One)

The ice trick is one of the quickest and easiest ways to determine whether or not your home is humid.

Of course, this method does not gauge specific humidity levels, but it does a wonderful job of telling you whether individual rooms in your home are dry or humid.

Certain rooms in your home (such as your bathroom or kitchen) are extremely volatile in terms of humidity, so you may want to consider starting this technique in another room.

To do it, all you need is one glass of water and four ice cubes.

Take this mixture and leave it in a room with nobody in it.

You, too, should exit the room, as your presence or movement could cause the humidity levels to change. Stay out of the room for around five minutes before coming back in.

When you return to the room, it’s time to evaluate the glass. If there is thick condensation around the outside of the glass, you know that the room is too humid.

Remember, humidity refers to moisture, so the presence of water on the outside of the glass is proof that there is too much moisture going into the atmosphere.

If there is no condensation at all on the outside of the glass, you can know that the room is too dry.

Both of these are problems; however, if your glass appears to be in the middle ground of this, you should be okay.

This ice test is a simple and virtually free way to make sure that the air levels in your home are neither too humid nor too dry.

If you find yourself lacking a hygrometer, consider trying out this trick so that you can test the humidity levels in your home whenever you want.

The Ice Trick (Part Two)

This variation of the ice trick is a great way to gain a more accurate idea of just how humid it is in your house.

To perform it, you’ll need a metal trash can, water, ice, and a simple thermometer.

The goal of the experiment is to find out the dew point temperature, a term that refers to the point at which water saturates the air fully and water vapor subsequently condenses.

You’ll want to use a metal can, as it’s the best at keeping both heat and light away.

Fill the can about two-thirds full with water, then begin to fill it with ice. You’ll want to do this slowly, stirring the mixture with your thermometer.

Let the ice melt completely and continue to add more until you notice water beginning to condense on the outside of the can.

At this point, you simply need to read the temperature on the thermometer. This reading will be your dew point temperature, and high numbers will be indicative of large amounts of water vapor in the air.

In other words, higher readings mean that your room is too humid, and lower readings meant that your room is too dry.

Also Read: Why Does Humidity Increases in Summer?

The Double Bulb Experiment

If you’re looking to get an even more accurate reading, consider trying this experiment.

To do it, you will need two mercury thermometers, a piece of cardboard, cotton, and duct tape.

To start, make sure that both of your thermometers have the mercury down in their bulbs (the bottom part of the device). You may need to shake the thermometers to ensure this.

Once done, take a piece of cotton moistened with room temperature water and wrap it around the bulb of one of the thermometers.

When this is done, attach both of the thermometers to your cardboard with the bulbs sticking out, using your duct tape to do so.

The next step is to go into the room you plan on checking to place the thermometers in front of a fan for five minutes.

You will want to leave the room during the process so as not to create an unnecessary disturbance.

Come back in after five minutes and take records of both thermometers.

Then, subtract the temperature of the wet-bulb from the temperature of the dry bulb to find the humidity percentage.

If the dry bulb is 26 degrees C and the wet bulb is 15 degrees C, for instance, you would subtract the latter value from the first and come up with a “depression” of 11 degrees C.

Record this depression value also.

Here’s the fun part.

With these values, find the intersection of the dry-bulb temperature and the depression temperature in a relative humidity chart such as this one and find the relative humidity of your room.

This will give you a more or less accurate hygrometric reading.

In the scenario described above, this reading would end up being 28 percent, which is a little on the dry side.

The Hair Trick

The hair trick is one of the more fun experiments you can do, and it gives you a surprisingly accurate reading.

With just a few simple tools, including your own hair, you’ll be able to accurately gauge the relative humidity of your room.

Specifically, you’ll need a strand of human hair, a paper arrow, a piece of cardboard, two tacks, a spray bottle, and a blow dryer.

Start by cutting an arrow out of a sheet of paper.

For the next step, you’ll want to tack one end of the hair to the cardboard; following this, wrap the other end around the arrow, which should be tacked into the cardboard.

You want to make sure that your arrow is able to move with absolutely zero friction. This is key to getting an accurate reading.

Here’s the fun part: human hair expands when it becomes exposed to moisture.

As such, we can reason that, when absent of all moisture, the length of the hair will be shorter than when it’s properly saturated.

These two points represent the extremes on which you can gauge your hydrometer.

To accurately chart these points, you’ll want to first blow-dry the hair until it is perfectly dry.

This should tilt the arrow upwards (assuming that the hair contained moisture). Mark this point as “zero” and let it represent the bottom of your hygrometric range.

Then, saturate the hair with a spray bottle until the arrow swings as far downward as possible. Mark this as “one hundred” and let it be maximum relative humidity.

Once you’ve done this, you can graph out the percentages in between and give your homemade hygrometer time to adjust to the environment.

After several hours of undisturbed reading, it should be able to give you a more or less accurate reading.

Remember that higher numbers represent higher relative humidity and lower numbers mean your air is on the drier side.

The Bottom Line

Testing the humidity levels in your home is easier than you think. Even without a hygrometer, there are tons of ways you can make sure that your home is not too humid.

By following the information in this guide, you can successfully measure the relative humidity in your home to know whether or not your abode is too humid.

As this is the first step to taking steps to correct your indoor climate, it’s important that you follow through to find out just what type of air you are taking in.

So, don’t wait!

If you’re wanting to test the humidity levels in your house, use this guide as your reference point today.