Ultrasonic vs. Evaporative Humidifier: Understanding the Key Differences

When winter arrives, you usually know it since your lips and skin start drying out and becoming uncomfortable.

But dry air can do more than just cause dry and cracking skin; it can also cause or exacerbate respiratory problems. Not to mention there are a myriad other health issues that come along with it.

One easy and quick way to make your household more comfortable and healthier is to use a humidifier. But there are several types available, including ultrasonic and evaporative.

Are you wondering about the differences between an ultrasonic vs. evaporative humidifier? In this article, we'll discuss the difference between these two so you can make the best choice for your household.

What Is a Humidifier?

Before we get into the details of ultrasonic and evaporative humidifiers, perhaps we should first quickly define what a humidifier even is.

A humidifier is a device that disperses tiny water particles into the air. What this does is raise the humidity in the air. In most cases, these devices are portable, which means you can easily move them from one area of the house to another.

What is humidity? Humidity is how much water vapor is present in the air.

When there's low humidity, you might notice your skin drying out and you may get nosebleeds. And when there's high humidity, you might feel like the air's bogged down, that it's hard to breathe, and that it's very moist out.

As you can see, there's a delicate balance when it comes to humidity. You may have already guessed that in addition to humidifiers, there are also dehumidifiers. You can use these to lower the humidity in a room.

In general, there are 4 types of humidifiers: cool mist, warm mist, evaporative, and ultrasonic. For the purposes of this article, we'll tackle the last 2 in detail.

Cool and Warm Mist Humidifiers

Very quickly, we'll describe how warm and cool mist humidifiers so you have a basic understanding of your other choices.

Cool mist humidifiers are also known as impeller humidifiers or evaporative cool mist humidifiers. Inside, there's a spinning disc. When you turn on the device, it draws water up from the reservoir and turns it into a fine mist as it goes through the disc.

With warm mist (steam) humidifiers, there's a heating element in place of the spinning disc. The water in the reservoir is heated to boiling point and the humidifier then sprays the warm mist into the air.

What Is an Ultrasonic Humidifier?

An ultrasonic humidifier works like the mist humidifiers, but instead of a spinning disc or heating element, it has 2 ceramic plates.

These ceramic plates are vibrated at very high frequencies. That way, when the water gets drawn through, they're vibrated into ultra-fine water droplets that increase the air's humidity.

humidifier is in the bathroom

What Is an Evaporative Humidifier?

An evaporative humidifier's inner part is a wicking filter and fan. Once you switch on your device, it starts drawing water up from the reservoir into the basin. Then, the water is drawn through the wicking filter.

The fan then evaporates the water that's on the filter. This is what creates the mist of water droplets in the air.

Evaporative vs. Ultrasonic Humidifier Differences

Now that you have some basic information about both evaporative and ultrasonic humidifiers, you're probably wondering which one you should get for your house.

Do keep in mind that portable humidifiers can only humidify one room, so chances are, you'll have to purchase more than one to properly humidify your house. This means you can actually get both evaporative and ultrasonic humidifiers and choose which ones suit particular rooms.

Of course, you may find that in general, you prefer one over the other. This is why it's important to weigh the pros and cons of each type of humidifier before making your purchases.

Below are some factors you need to consider.

Noise Level

A very important factor to consider when you're looking at humidifiers is the noise level.

For example, if you want a device for your bedroom, you don't want something that emits a noticeable amount of noise, as it may make it more difficult to fall and stay asleep. This is especially true for people who are very sensitive to noise. However, it can provide a sort of white noise in the background, which may actually help some people fall asleep.

elderly woman stretches and smiles in bed

As you may remember, evaporative humidifiers use fans to operate. On the other hand, ultrasonic humidifiers operate solely on vibration, which means there are no fans. This doesn't mean they're completely silent; however, they emit a barely audible hum.

You need to consider all the parts that make up a fan. Obviously, these all cause an evaporative humidifier to be louder than an ultrasonic one. But if anything is improperly maintained, or if it just goes through normal wear and tear, that'll cause it to be louder than normal too.

So when you compare the noise levels of these two humidifier types, ultrasonic wins, hands down.

That is not to say that you shouldn't use evaporative humidifiers at all. For example, you can use it in the living room, where noise isn't really a big factor. And as you'll see from reading the rest of this article, there are pros of evaporative humidifiers that make it good to have.


Both evaporative and ultrasonic humidifiers are very safe when you compare them with, say, a warm mist humidifier. If you have pets and small children in the house, you won't want to have them accidentally run into the humidifier and get scalded by boiling water.

However, because these types of humidifiers don't boil water, it may mean that bacteria can grow more easily inside the reservoirs. This means you'll have to clean them more often than you would with a warm mist humidifier.

In general though, both types of humidifiers are very safe to use in any type of household.

Moisture on Floors

With ultrasonic humidifiers, they release fine water droplets instead of water vapor. Because of this, you may get damp spots on your floor.

To avoid this happening, you have to place ultrasonic humidifiers higher up, such as on tables or dressers. This gives the water droplets more time to evaporate before they hit the floor.

Because of this, you may be more limited in where you can place your ultrasonic humidifiers when compared to evaporative ones.


Both types of humidifiers are usually portable, which means their sizes are very manageable. This is especially true if you're planning on moving them from room to room a lot.

However, you can expect ultrasonic humidifiers to be smaller in size. This is because they're much simpler in design.

So if you want something very small and that's out of the way, then an ultrasonic humidifier may be better than an evaporative one. These can be great for people who are short on space.


With evaporative humidifiers, you need to replace the wicking filters every once in a while. You also need to either replace or wash the wick itself occasionally too.

With both types of humidifiers, you'll need to clean them regularly to ensure that bacteria and mold don't grow on the inside. If you live somewhere with hard water, you'll either have to put in more effort to clean your humidifiers and/or have a more frequent cleaning schedule.

With normal ultrasonic humidifiers, you won't have anything to replace. However, if you decide to go with one that uses ceramic cartridges, there will be a replacement schedule. This will probably still be less frequent than with wicking filters in evaporative humidifiers though.

Also, note that some ultrasonic humidifiers use advanced technology. In that case, you'll need to have a qualified technician perform maintenance. This leaves less work for you to do, but it'll be an added cost you need to factor in.

Mineral Scale Deposits

Because ultrasonic humidifiers don't have wicking filters, this means small particles (such as dust) aren't caught and filtered out before they disperse mist in the room. This means you'll likely see a gray dust in the air and room.

If you live in an area with particularly "hard" water, then you'll run into mineral scale deposits and gray dust in the air more often and on a more noticeable scale. However, if you have soft water, or just don't mind the gray dust, then you might still want to consider an ultrasonic humidifier over an evaporative one.

Do know that you can easily counteract hard water by using demineralized water. However, do note that this can be costly in the long run.

You can also try using a model that has ceramic cartridges. These can be replaced every so often.

For people who have allergies or respiratory conditions (such as asthma), evaporative humidifiers may be a better choice since they have a filter that'll keep dust and other particles out of the air.

But if you don't want to deal with the maintenance that comes with evaporative humidifiers, you can just get an ultrasonic humidifier and either use demineralized water and/or ceramic cartridges.


In this category, evaporative humidifiers have about the same lifespan as ultrasonic ones. This can be anywhere between 3 to 5 years.

The actual lifespan of your humidifier will depend on how well you take care of it. So for instance, if you buy an evaporative humidifier and you don't change out the filters as often as you should, then this can affect its lifespan.

The actual lifespan will also depend on which brand humidifier you get. Bigger brand names tend to have better working parts, but they tend to be more expensive as well.

So while both types of humidifiers are equal in this category, you have to think about and take into account how well you'll realistically maintain your device and which brands you're looking at.


Last, but not least, is the price difference between these two humidifiers.

As we've mentioned above, evaporative humidifiers need filters, while ultrasonic ones don't. Because of this, you won't have to spend extra money on buying filters throughout the lifespan of your ultrasonic humidifier.

Also, ultrasonic humidifiers tend to use much less electricity than evaporative humidifiers. If you're planning on having several humidifiers in your home, then the type(s) you choose can affect your utility bills.

However, do note that ultrasonic devices are more expensive when it comes to upfront prices. Of course, the exact difference in price will depend on the brand, features, and size.

In general, you shouldn't expect to see a huge price difference. But do know that ultrasonic humidifiers tend to cost more than ultrasonic ones. 

Ultrasonic vs. Evaporative Humidifier: Choose the Right One for You

When it comes to the debate between ultrasonic vs. evaporative humidifiers, both have their own pros and cons. While an ultrasonic humidifier may seem ideal for your friend, it may not necessarily be great for you.

You may also initially balk at the price of some ultrasonic humidifiers. But do keep in mind there are also lots of "hidden" costs of evaporative humidifiers, such as the cost of filters and higher energy consumption.

So weigh up the pros and cons yourself and determine what's best for you based on the information we've given you here. And if you ever feel like the other type would be better, you can always buy the other and try it out in a room to see if it's more suitable.

Would you like to get something that complements your humidifiers? Then consider getting an essential oil diffuser.

Leave a comment

Comments must be approved before appearing