Tips for Buying a Humidifier: 8 Things to Consider Beforehand

There are many humidifier options available on the market today and it can get confusing quickly. There are different humidifier types, sizes, and price points. They also vary on what kind of and how much maintenance they need. We’ll help sort out these small but important details in this humidifier buying guide, so you’re not left scratching your head at the many options.

Cool Mist or Warm Mist

The main difference between cool mist and warm mist humidifiers is that warm mist humidifiers boil the water before spreading it through the air. This helps clean the water before it’s spread through your room, which is beneficial in reducing bacteria and mold. It can help keep the air clean.

Conversely, a cool mist humidifier keeps the water at room temperature and disperses it through the air. This is safer for humidifiers kept in the reach of kids or pets, since the water in the water tank is not hot.

Humidifier Size

There are many size options for humidifiers, so choose one that suits your needs. Most sizes are described with a square footage capacity, so you may need to take measurements of your room(s) before shopping. You might also see descriptions of water tank sizes, such as “1-gallon”. This is more of a convenience factor rather than a size factor, and we’ll discuss the significance of tank sizes later in this article.

Personal/Compact Humidifiers


The smallest humidifiers are for personal use or use in a small room of 400 square feet or less. They are also called portable or compact humidifiers. These are lightweight, come with a small refillable water tank, and can be used on your desk. Sometimes these are battery operated or can be plugged into the wall, which make them great for traveling.

Medium Sized Humidifiers

Medium-sized humidifiers are best used in spaces between 400-1000 square feet. They’re also called tower humidifiers. The nice thing about this size is that you don’t have to refill it as often as the smaller humidifiers, since the water tank is generally larger.

Large Humidifiers

Large humidifiers are also called console or tower humidifiers and are best used for multiple rooms or areas larger than 1000 square feet. Again, you won’t have to refill the tank as often because it comes with a larger water tank. You can move these around if you want, but keep in mind that they are heavy.

Whole House Humidifiers

The largest humidifiers you can buy are whole house humidifiers, which are also called online, console, in-duct, or flow-through bypass units—meaning that the humidity is passed through the house through the ducts. This will maintain humidity in all rooms of the house.

Whole house humidifiers usually come with a humidistat that measures and controls the humidity in the air, so you can set it and leave it. These are usually mounted near the HVAC system in a house, so they are not portable. You may be able to find some with wheels, but even then, their portability is reduced because of their weight.

Humidification Process: Evaporative vs. Ultrasonic Humidifiers

Not all humidifiers work the same. Some create mist by evaporation, while others use sound waves—these are called ultrasonic. Ultrasonic humidifiers send vibrations through the water to create a fine mist that’s dispersed through the air. The benefit is that the water is not being heated, so they are generally safer to keep around kids and pets.

However, the tradeoff is that the mist may be less clean than the mist produced by evaporative humidifiers. Since evaporative humidifiers heat the water, the mist is cleaner and has less bacteria. Another bonus is that evaporative humidifiers are generally cheaper.

Humidity Controls

In order to maintain a comfortable level of humidity, some humidifiers come with hygrometers and humidistats. A hygrometer measures the humidity level in the air, while a humidistat actually controls the level of humidity in the air, often by working with the home’s HVAC system.

With a whole house humidifier, you’ll want a humidistat but with a small or personal humidifier, you don’t need a humidistat, or even a hygrometer. Most small humidifiers will come with variable settings, such as low, medium, and high—which you can easily adjust to your comfort level. Of course, some high-end, pricier models have these features and are handy if you want increased control.

Water Tank Size

All humidifiers come with a water tank, and the size is important because it determines how often you need to refill the tank. Small humidifiers have tanks of 1 liter in size to 5+ gallons. A 1-liter tank will require a refill approximately every 7-8 hours, while a 4-gallon tank can last for 24 hours.

Another factor that determines how often you need to refill the tank is the setting you prefer—if you always have the humidifier set to the max, you’ll need to refill the tank more often. Determine what tank size is most convenient to you. Keep in mind that a larger tank also decreases portability.

Humidifier Maintenance

Humidifiers require regular cleaning, and this is key to keeping the air free of bacteria and mold. Depending on your humidifier, maintenance might include regularly changing the filter and cleaning the water tank. It’s best to follow the instructions on your humidifier’s manual to determine how often you need to perform these tasks.

Changing Your Humidifier’s Filter

Most humidifiers come with a filter or a wick through which water passes before it’s evaporated to become mist. Smaller units will require you to change the filter more often, so buy some filter replacements along with the humidifier.

Cleaning Your Humidifier

kitchen sink

You may need to regularly clean your humidifier with chemicals. Some humidifier cleaning guides online recommend chemicals like bleach, hydrogen peroxide, or white vinegar. Again, check with your manual. If this is time consuming, remember that some humidifiers come with parts can be washed in your dishwasher and are ready to use again; this makes cleaning a much faster and easier process. Take a look at our easy to clean humidifier guide if you’re looking for a unit with less hassle.

Refilling Your Humidifier’s Water Tank

Regular maintenance also includes changing your water if it’s not completely used up. You need to remove the old water and replace it with fresh water. This helps prevent the stagnant water from building up with bacteria.

Managing Mineral Deposits

Ultrasonic humidifiers dispel white dust which is actually mineral deposits from the water. There are a few solutions to this, including using demineralizing cartridges/tablets. You can also use distilled water.


If it’s after allergy season and you want to store your humidifier, make sure you clean and dry it completely before storing. Otherwise it can become a breeding ground for bacteria and mold. Remember to clean it once more before using it again.  

Other Considerations

There are a few other things to consider when purchasing a humidifier, such as noise level. You’ll also want to look into warranties, especially if you choose a higher-priced humidifier.

Noise Level

Most humidifiers make noise since the water may be boiling and creating a hissing sound when the mist is dispersed into the air. Ultrasonic units are somewhat quieter than evaporative units because they do not heat water. Keeping the humidifier at the lowest setting may help reduce the noise level, especially at night. Before buying, check with the reviews and the unit’s decibel score.

Decibels & What A Score Sounds Like

Humidifier manufacturers describe noise level in decibels. Most humidifiers seem to stay under 40 decibels. To understand what these levels sound like, we’ve included some decibel sound descriptions, found through IAC Acoustics: 10 decibels are likened to the sound of breathing and can barely be heard or noticed. 20 decibels are likened to a whisper; 30 decibels are described as very quiet; and 40 decibels are likened to the sound of a library.


Some humidifiers come with warranties, and they can be useful. They are most useful for larger, more expensive units such as whole house humidifiers. Determine whether you want to stick with the regular warranty, or spring for the extended warranty, as many manufacturers offer both options.

Buying Humidifiers

We tried to make this a comprehensive guide of what kinds of things you’ll need to consider before buying a humidifier. Although there are many options on the market, we hope this guide simplified some of the process. For humidifier recommendations, check out our humidifier buying guides below:

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