Informational Guide

Comparing Ultrasonic Vs Evaporative Humidifiers

Not sure which type of humidifier is for you? We explore the difference between ultrasonic and evaporative humidifiers so you can make an informed choice.

by Josh M

If the air in your home is drier, it can cause coughing, dry skin, and nosebleeds. Studies say the humidity in your home should be about 30-50%.

Not sure which humidifier is for you? Stay tuned! In this guide, we will explore ultrasonic and evaporative humidifiers to help you make an informed choice.

An ultrasonic humidifier works with two ceramic plates underneath a basin of water, often called the diaphragm. The two plates vibrate at a high frequency to separate the water into microscopic droplets released into the air, increasing the humidity of a room.

The vibration is above the frequency of human hearing and so is silent. They are often called ‘cool mist’ humidifiers as there are no heating elements inside.

Dehumidifier with Aroma

Pros & Cons of Ultrasonic Humidifiers

What We Like
  • Smaller: because of its simple design, they take up less space.
  • Safer: they work from cool water, so there are no heating elements. This may be safer in a home with small children or pets.
  • Cheaper: because of their design, they don’t have excess costs along with purchase.
  • Less Maintenance: you don’t need to change any filter or wick; the water droplets are propelled through the vibrations.
  • Lower Electricity: they won’t eat away at your electricity bill as they take little power to run.
  • Silent: the vibration frequency is beyond the level of human hearing, so it is better for a bedroom as they quietly hum.
What We Don’t Like
  • Extra Water: water is released in droplets which can settle outside humidifier before evaporated.
  • Minerals: with hard water, excess minerals can be released into the air, which can dry out and create a white dust.
  • Less Hygienic: there is no filter, so biological or allergenic contaminants could be released into the air.
  • Over-humidification: the droplets in the air sometimes don’t evaporate, which could attract mold or mildew if it becomes excessive.

What is an Evaporative Humidifier?

An evaporative humidifier works with a wicking filter and a fan. Water is drawn out from a basin into the wick, which a fan blows to evaporate the water into the air, increasing humidity.

There are two types of evaporative humidifiers; a cool air humidifier, using cool water, and a warm air humidifier, which warms the water over a heating element underneath. They’re designed to be used in multiple temperatures.

Dehumidy Room

Pros & Cons of Evaporative Humidifiers

What We Like
  • Vapor: the water is released as a finer vapor, meaning there’s no mess from humidifying.
  • Cleaner: the filter inside purifies the water before it is evaporated; it won’t release bacterial or allergenic contaminants.
  • Softer Water: the wick and filter will draw out the excess minerals in hard water, releasing soft water into your room.
  • Warmer: evaporative humidifiers work with either cool or warm water, making them better for warmer climates or colder months.
  • Less water: some models can draw the unused water in from the air to be reused in the basin.
What We Don’t Like
  • Bigger: the design is larger than an ultrasonic, meaning it takes more space in a room.
  • Maintenance: the filter and wick will need regularly changing to avoid any contaminants being released.
  • Expensive: the initial price is low, but the cost of replacement filters can rack up the price. You should wash filters every 3 days.
  • Noisier: the fan running will be louder than an ultrasonic, which might not be ideal for a bedroom or living room.

Ultrasonic vs. Evaporative Humidifiers: Key Differences Explained

Warm vs. Cool

A major difference is that evaporative humidifiers are more likely to have heaters than ultrasonic. This gives you a better range for temperatures. If you live in a warmer climate, then you’ll want warmer water to humidify a room. There are very few ultrasonic humidifiers with warm water, giving you fewer options.

Noise Level

Because of their larger design, evaporative humidifiers are louder than ultrasonic. The sound from the fan running emits more noise, whereas an ultrasonic only uses two plates to vibrate and push droplets into the air. Ultrasonic may be a better choice for bedrooms, for a quieter atmosphere.


Evaporative humidifiers are larger and can come with heating elements. Depending on where you place your humidifier, you can potentially be scalded or burned if it’s knocked over. This is particularly a problem with small children or pets around. Ultrasonics are smaller and can be placed out of the way.


With the filter and wick, evaporative humidifiers will remove allergenic or bacterial contaminants from the water. This is then sent into the air will be cleaner and better for your lungs. Ultrasonic humidifiers don’t come with a filter and so will emit the contaminants into the air if they’re present.

Mineral Deposits

If you live in an area with hard water, an ultrasonic humidifier will release droplets with the excess minerals into the air. If they aren’t evaporated, they can dry up and create a white dust-like layer in your room. Evaporative humidifiers will filter out the excess minerals and release softer water into the air.


It would be best if you regularly cleaned whichever you decide to buy. With an ultrasonic, it requires less cleaning as you will need to wipe and sanitize the basin and check for mold and mildew. With an evaporative model, you will need to change the wick and filter every so often to keep it functional.


Consider the size of your humidifier if you intend to use it in multiple rooms. In terms of ultrasonic vs. evaporative humidifiers, the ultrasonic is smaller in design, so it should be easier to move around your home where needed. Evaporative humidifiers can come in smaller designs but might be too small for your desired humidity.


When it comes to the outright purchase, ultrasonic humidifiers tend to be more expensive. They do, however, come with fewer maintenance costs as there is no filter to replace. Ultrasonic also tends to use less electricity. Evaporative requires the filter changing, which, in terms of price, can buildup if you use it regularly.

Water Droplets on Glass or Window

Comparing Ultrasonic & Evaporative Humidifiers for a Baby

Humidifiers can alleviate cold and flu symptoms for babies. If you’re choosing an ultrasonic model, a white dust can coat the child’s room. Using filtered water will eliminate this, meaning less cleaning.

Evaporative models give you the choice of warm or cool mist, depending on the temperature. Be careful that your child doesn’t scald or burn themselves when using warm mist; it’s best to store it out of reach.

People Also Ask (FAQ)

Does a cool mist humidifier make the room colder?

No. Using a cool mist humidifier will actually help you to retain your body heat, which will, in turn, make you feel warmer. To cool your room, consider using a fan.

Can I use filtered water instead of distilled water?

If you are in an area with hard water, distilled will be better as it won’t have the minerals present in harder water. You can opt for filtered if you live with softer water.

Do cool mist humidifiers help sinuses?

In short, yes! Humidifiers will relieve congestion in your sinuses by opening up the nasal passages and help you to breathe easier.

Does a humidifier help with coughs and phlegm?

Yes. A humidifier will break up the mucous inside of your nose and lungs, making it much easier for you to cough up. They will also help with a dry throat.

Where should I place a humidifier?

You should place your humidifier near to people, but not where it could cause a hazard. Placing it on a shelf or side table will work but be careful of what you put around it; if the humidifier leaks, this could cause damage to your belongings. Find out more about where to put these devices in this article.


When it comes to ultrasonic humidifiers vs. evaporative, the answer comes down to personal choice. If you’re looking for an option for temperature, then evaporative is your best bet. Ultrasonic is better for a quieter operation, or you need extra humidification. Your choices are endless for better breathing!

Last Updated on December 23, 2022

Josh M

My name is Josh and I am obsessed with the HVAC industry. I created this website to help HVAC techs of all levels get the best out of their heating & cooling systems. I have spent thousands of hours studying air conditioners, heaters and home air products so you can learn & buy with confidence. Learn more about the team here.