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Humidifier Vs. Dehumidifier: What’s The Difference?

Updated on December 15, 2022
Written by
Danny Ashton
Danny is the founder of HouseFresh and has been writing about air purifiers and indoor air quality since 2010. He is our lead tester, conducting all the tests we use to evaluate air quality products. That is why you will always see his name attached to our reviews.

Humidifier Vs. Dehumidifier. What’s the difference? Even though the words sound similar and may seem to have similar meanings, their differences become obvious once we start discussing their functions, types, and the benefits of each.

How much humidity should a house have?

If you are reading this, you probably have no idea how moist or dry the air in your home is. Most people don’t notice until they experience one extreme or another. Have you noticed that your skin is bleeding and cracking for no discernible reason? Then it could be the dry air. Do you sometimes get out of the shower and cannot get the moisture off of your body? If this is the case, chances are your home is humid.

Measuring the amount of moisture in the air is done by using RH or relative humidity. Relative humidity refers to the amount of water vapor in the air concerning how cool or hot the temperature is. When it comes to a comfortable RH level, the range should be between 30 to 50%. If your home has more than 50% relative humidity, you will need to get a dehumidifier to remove moisture from the air. Failure to do so could spur bacterial growth. If your home has a relative humidity of less than 30%, the air is quite dry, and you need a humidifier to put some moisture into the air.

For the most part, the climate helps us control relative humidity. Nevertheless, there are extreme cases where the air is too dry or too humid, resulting in symptoms such as fatigue, shortness of breath, and coughing. These extremes can even worsen respiratory conditions such as asthma or allergies by drying out your airways.

How do you find out how humid your house is?

Measuring the humidity levels in your home is actually relatively easy. There are a plethora of methods to do this. However, we are only going to focus on the less complicated procedures. You can measure humidity in your home by getting a hygrometer.

A hygrometer is a device that measures humidity in an environment. It works using the principle of evaporative cooling. When water evaporates from a surface, it becomes cool due to molecules taking heat from that surface. The most effective way to get an accurate reading is by picking the right location. Make sure to find a room that doesn’t experience wide humidity or temperature fluctuations, take measurements over a week in various rooms to develop a baseline, and take readings at different times of the day.

What does humidity do to your house?

High humidity in your home can spur the growth of mildew and mold, while excessive moisture could result in rot, causing your belongings to become damaged. Apart from the growth of mildew and mold, high humidity could also cause your wallpaper to peel and any paintings or artwork to become damaged.

Excess moisture in your home can damage wood, either creating growths and stains or causing severe decay. Furniture placed closer to outside walls are at a higher risk of damp setting in.

Types of Humidifier

When it comes to humidifiers, there are two major types: warm-mist and cool-mist. Both equally add moisture to the air. The type of humidifier you choose is simply based on personal preference, as one doesn’t have an advantage over the other.

Warm-mist humidifiers use a disc in water that spins at high speeds, generating tiny water droplets that exit the humidifier in the form of steam. Cool-mist humidifiers either blow cool air through a wet object to moisturize the air or use a plate made from metal or ceramic known as a diaphragm. The diaphragm vibrates at high speeds stirring up water into droplets when they exit the humidifier.

Types of Dehumidifier

As stated earlier, dehumidifiers do the opposite of what humidifiers do. They take moisture out of the air, keeping the air indoors dry. A well-functioning dehumidifier should reduce the indoor RH to a 30 to 50% comfortable range. When it comes to dehumidifiers, there are two types: desiccant and refrigerative.

– Refrigerative

Refrigerative dehumidifiers are the most common types of dehumidifiers used in households. They don’t offer as much cooling power as a desiccant. However, they can seamlessly maintain a healthy humidity level in a home.

The fan in the dehumidifier captures and contains warm air, cooling it using metal coils. As the warm air is cooled down by the refrigerant-filled metal coils, the air begins to shrink, producing warm water droplets, which are then stored as condensation in the dehumidifier’s tank. With the cold air now free of warm water droplets, it gets blown back into the home by another fan. 

– Desiccant

Desiccant dehumidifiers are extremely powerful dehumidifiers. For this reason, they are typically used in commercial storage such as chemicals, food, and pharmaceuticals. A desiccant can reduce the humidity levels from 45% down to 1%. Compared to a refrigerative dehumidifier that uses electrical outlets, a desiccant dehumidifier uses thermal energy (steam or natural gas). It also differs from a refrigerative dehumidifier in how it gets rid of moisture. It uses chemical attraction rather than condensation to decrease humidity levels.


They both deal with the humidity levels in your home; however, a humidifier adds moisture to the air while a dehumidifier removes moisture from the air. The device you use typically depends on the Relative Humidity level of your home.

TLDR: You might struggle with humidity in your home but have no idea how to handle it and which machine to get. Humidifiers add moisture to the air, raising the humidity levels, while dehumidifiers remove moisture.


Humidifier Benefits – 15 Excellent reasons Why in 2020 (2020). Purify This.

The Benefits of Using a Humidifer (2021). Aurum Cosmetics at Berkeley.

How humidity damages your home – and how to fight it (2021). Air Things.

How To Measure Humidity Indoors? (With and Without a Hygrometer). Cool Mist Humidifier.

What is a Hygrometer and How Does It Work (2021). The Weather Makers.

About the author

Danny Ashton

Danny is the founder of HouseFresh and has been writing about air purifiers and indoor air quality since 2010. He is our lead tester, conducting all the tests we use to evaluate air quality products. That is why you will always see his name attached to our reviews.