Informational Guide

How Do Ultrasonic Humidifier Work?

This guide will show you how ultrasonic humidifiers work and why they help you fight the dry winter days. Improve the air quality inside your house today.

by Josh M

During the winter season, there is a general lack of humidity in the air. This affects not only the outdoor air but also the indoor air in your home. Humidifiers can help improve air quality inside your house during the cooler months by adding moisture back into the environment.

This guide will show you how ultrasonic humidifiers work and why they help you fight the dry winter days.

Cozy Bed and Wooden Bedside Table with Stack of Books

Ultrasonic humidifiers are similar to other types of humidifiers, but they use ultrasonic sound waves to create the water droplets that leave the device. Other humidifiers use heat. Ultrasonic humidifiers work well for most people and will absolutely keep your home at comfortable humidity levels.

Ultrasonic humidifiers are exceptional at adding moisture to the air and can sometimes over-hydrate the air, so it’s essential to always set your ultrasonic humidity level before letting the machine run (so it can auto-shutoff when it reaches the desired humidity level).

How Do Ultrasonic Humidifiers Work? (Science Behind Them)

Principle of Operation

The principles of operation for an ultrasonic humidifier is simple. The internal body has a water reservoir and a vibrating mechanism. When the unit is turned on, the vibrations create water droplets that can then be sent through the unit in a cool mist to increase humidity levels.

Principle of Humidification

There are two primary principles of humidification when it comes to ultrasonic humidifiers: cavitation bubble implosion and capillary wave theory.

Cavitation bubble implosion: The cavitation bubble implosion is another humidification process that can be seen with ultrasonic humidifiers. This process involves using the oscillator in the machine and changing the amplitude so that the water creates tiny cavitation bubbles. These bubbles on the surface of the water send water aerosols into the air.

Capillary wave theory: The capillary wave theory is involved in the humidification process with ultrasonic humidifiers because this is how these units are able to bring water aerosols into the air. The water tank creates surface waves that are used to carry water droplets into the air (off of the small wave).

Principle of Humidification
Ultrasonic Humidifier vs. Evaporative Humidifier – What’s the Difference?

The primary difference between an evaporative humidifier and an ultrasonic humidifier is how they hydrate the air. Ultrasonic humidifiers use vibrations to create water droplets that are then sent out of the machine and into the air.

Evaporative humidifiers use heat to evaporate the water. They then will either send it out through hot mist or have an internal mechanism (often a fan) that cools the water before sending it out as cool mist. Ultrasonic humidifiers use a much simpler method and, therefore, can be smaller and more compact than other humidifiers.

Learn more about these 2 types of humidifiers in this guide.

Pros and Cons of Ultrasonic Humidifiers

What We Like
  • Exceptional at humidifying the air
  • Small, quiet, & compact
  • Great at virus control
  • No heat, which makes them safer
  • Good for your skin
  • Easy to maintain
What We Don’t Like
  • No filter for mineral scale absorption
  • Can “over humidify” if there isn’t a humidity sensor feature
  • More expensive
  • Possible bacterial contamination if not regularly cleaned

How To Make An Ultrasonic Humidifier More Effective

To make your unit the most effective that it can be, there are a few things that you can do at home.

Clean Your Ultrasonic Humidifier Regularly

If you do not clean your unit regularly, you are likely to create bacterial contamination. This can lead to germs being sent directly into your air and circulating throughout your home. We recommend cleaning your entire unit (including your water reservoir) every week.

Don’t Use Tap Water, Only Distilled Water

Too many people think that they can use tap water with their ultrasonic humidifier. However, the reality is that tap water has numerous minerals in it. If you use tap water, you will experience more of the frustrating mineral dust that humidifiers often leave around the house.

That white mineral dust can require extra cleaning, and you will find less of it around your home if you use distilled water.

Don’t Place an Ultrasonic Humidifier in a Small Enclosed Area

If you place your unit in a small enclosed area, the area may become too high in humidity levels too quickly. Why? Ultrasonic humidifiers are fantastic at humidifying the air and can quickly create high humidity levels in a small, enclosed space. Give your unit more space.

Place it in a Secure Location

Make sure that you do not place your humidifier on the floor where animals or kids can interfere. It is also essential to place your unit on a plastic tray or piece of furniture where it is elevated in the room. This helps the water droplets spread more effectively and efficiently.

See our in-depth placement guide.

Always Have Your Humidistat Setting On

The ultrasonic humidifier is notorious for quickly increasing the humidity levels of a room. When this happens, the room can become too high in humidity, leading to mold or other bacteria problems.

The best way to avoid this and make sure your home stays at optimal humidity levels is to set the humidistat level so that your humidifier can monitor itself.

Dehumidy Room

People Also Ask (FAQ)

Is it safe to use an ultrasonic humidifier in a baby’s room?

Yes, an ultrasonic humidifier is safe to use in a baby’s room, but we recommend only using cool mist humidifiers. The American Academy of Pediatrics warns against hot mist humidifiers because of the potential as a burn risk.

What is the difference between an ultrasonic humidifier and a diffuser?

A diffuser is a much smaller device used with essential oils to add fragrance and scent to a room. Ultrasonic humidifiers work by adding moisture back into the air. Learn more here.

Which is better: cool mist or ultrasonic humidifier?

An ultrasonic humidifier can have a cool mist or hot mist. Ultrasonic humidifiers are called ultrasonic because of the way that they work. They create a high-frequency mechanical vibration in the water that allows the water to form as droplets.

These droplets then move out of the humidifier as mist. Ultrasonic humidifiers tend to be quieter than fan-oriented cool mist humidifiers.

See cool mist models here

See warm mist models here

What kind of humidifier do I need for congestion?

If you suffer from congestion, a humidifier with a cool mist is best. Cool mist humidifiers have been shown to help with congestion and coughing more so than warm mist humidifiers, reports MayoClinic (though more studies are needed to fully confirm).


An ultrasonic humidifier is a state-of-the-art humidifier that is quiet, helps relieve congestion and cough symptoms, provides a more restful sleep by moisturizing airways, and can create a more comfortable home environment.

Ultrasonic humidifier technology will keep you from drying out your skin and airways during the winter months with clean, efficient technology.

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.