Can A Diffuser Be Used As A Humidifier?

This article discusses using a diffuser as a humidifier. 

Humidifiers and diffusers work around the same idea. Both diffuse a liquid into vapor or mist form and then release it into the air. In fact, many of the mechanisms and internal components they use are the same. 

Humidifiers are only designed to diffuse water, whereas essential oil/fragrance diffusers use both water and the actual fragrance or oil. 

You can technically use a diffuser as a humidifier, though there are some important caveats that we’ll get into below. 

We’ve been researching and reviewing humidifiers for a while. So if you were scratching your head about something related to humidifiers, we’ve got you covered. 

Keep reading for more information about using diffusers as humidifiers and vice versa. 

Can A Diffuser Humidify A Space?

An essential oil diffuser can be used to humidify a space. That said, it won’t be particularly effective and pales compared to an actual humidifier. 

But before we discuss how a diffuser can be used as a humidifier, we must first figure out how the two work, what humidification even is, and what you need to consider before using a diffuser as a humidifier. 

How Humidifiers Work

Humidifiers have a pretty straightforward design. They usually consist of a tank that holds water, some kind of mechanism that diffuses water, such as an ultrasonic setup, and a fan or something similar that releases the mist into the air. 

Once in the air, the mist increases the relative humidity of a space. If you aren’t familiar with relative humidity, it measures how much water a given volume of air at a specific temperature is holding compared to how much water it COULD hold. 

For example, say 1 cubic meter of air at 25 C can hold a maximum of 22 ml of water. Now, say that the same volume of air at the same temperature is holding 11 ml of water. In that case, we say that the relative humidity is 50%. 

Most people are comfortable at around 30%-50% relative humidity. Relative humidity lower than 30% can cause dry throat, coughing, dry/cracked skin, and many other problems. 

That’s where a humidifier comes in. It increases the relative humidity of the air in a room and makes it more comfortable for us. 

How Diffusers Work

Diffusers work much the same way as humidifiers. They also diffuse water into the air and bring up the humidity. 

The notable difference is that diffusers also diffuse essential oils, fragrances, and other aromas into the air, whereas humidifiers only diffuse water. 

When an essential oil diffuser converts water into vapor, it also diffuses the fragrance. The essential oil particles essentially ‘ride’ the water vapors and spread around a space. 

If you want to use your diffuser as a humidifier, simply fill it with water, skip the essential oils or other fragrances, and voila! 

Humidifier vs. Diffuser for Humidification

So now that we know how both humidifiers and diffusers work, it becomes obvious that a diffuser can be used as a humidifier. 

But some features and capabilities still make a humidifier better for humidifying a space than a diffuser. So let’s get into it. 

Firstly, a humidifier will be significantly better for increasing the relative humidity of a space. Most humidifiers are larger than essential oil diffusers. That means the water tank in a humidifier is also larger. 

Ultimately, the larger tank gives humidifiers a longer runtime and improved coverage of larger areas. 

Furthermore, essential oil diffusers do not need the highest mist volume since they can spread the fragrance around a room with minimal effort. Humidifiers are a different story. 

A humidifier needs to be able to cover larger spaces to increase relative humidity effectively. Humidifiers do so by having higher mist volume settings. Most modern humidifiers can easily produce mist at a rate of 200 ml/hr to 600 ml/hr. 

Essential oil diffusers don’t even come close to those levels. Plus, most humidifiers allow you to choose from different humidity levels, speeds, and mist volumes. 

Essential oil diffusers don’t give you nearly as much control; if they do, it is very limited. 

Another important consideration is that humidifiers have different modes and features that improve their efficiency compared to diffusers. For example, a lot of humidifiers have cool and warm mist modes. 

So, to sum up, an essential oil diffuser can be used to humidify a space. Still, a humidifier will always be the better option if you want faster, more consistent humidification over a larger space. 

An essential oil diffuser can technically increase relative humidity, but the effect is so weak in most cases that it is barely noticeable!

Can A Humidifier Be Used To Diffuse Essential Oils?

We learned that a diffuser can be used as a humidifier. So is the opposite also true? 

Well, yes and no. Generally, most humidifiers cannot and should not be used to diffuse essential oils. This is because the internal components inside a humidifier are designed for the sole purpose of diffusing water. 

The viscosity of essential oils differs from that of water. Moreover, the internal components in an essential oil diffuser are designed to be used with these oils. 

If you were to use essential oils in a humidifier, they could corrode or damage the internal components of your unit. 

In fact, you should never, under any circumstances, put essential oils or other fragrances into the water tank of a humidifier. There’s a reason it’s called a water tank, and if you put essential oils in it, it could cause problems. 

So then, are humidifiers completely useless when it comes to diffusing essential oils? 

Not so fast! While most humidifiers cannot diffuse essential oils, there are some specific models that come with that functionality. This may even be called ‘aromatherapy’. 

Some humidifiers come with an ‘aroma tray’ or similar components. Again, you should never put essential oils directly into the water tank of your humidifier. Instead, you put the essential oil into the ‘aroma tray’, and then the humidifier automatically diffuses it into the air. 

How To Humidify A Space Without A Humidifier Or A Diffuser

Say you don’t want to use a humidifier or a diffuser to increase the relative humidity of a space. What else can you do? 

Well, a humidifier is by far the most effective way of increasing relative humidity. It also has unique features that make the humidification process that much easier and more effective. 

But there are some other ways to increase the relative humidity of a space. 

Cook Or Boil Water Without A Lid

When you cook using water or boil it, some of the water escapes into the air in the form of water vapor. 

This water vapor then increases the relative humidity and makes your surroundings a bit more comfortable. 

But if you want to maintain that humidity level, you will need to keep boiling water so that it can continuously increase the relative humidity. 

You could incur quite the utility bill with this method. Not to mention, you have no control over the speed, humidity level, coverage area, or mist temperature. 

Keep Houseplants

Keeping houseplants can actually increase the relative humidity of your home. This is thanks to a phenomenon called ‘evapotranspiration’. 

Plants move water from the soil to the roots, and from there, it goes to the surface of the leaves. This process is called ‘transpiration.’ Once it gets to the leaves, water is evaporated into the surrounding air, thus increasing the relative humidity; ‘evapo-transpiration.’

This method does have an effect on humidity but really isn’t the best way to increase the relative humidity of a space consistently. 

Plus, there’s also the fact that you will have to take care of the plants, which might be a hassle for some folks. 

Leave The Door Open After A Shower

Another way to increase relative humidity is to leave the bathroom door open after you shower. Excess moisture from your shower moves out into the room, where it increases the relative humidity. 

Again, this method is only effective for a little while after your shower. And while we highly recommend that everyone shower twice a day, even we have to draw the line there. 

Other disadvantages are as you’d expect: no control over the level of humidity, the speed at which humidification takes effect, or anything else. 


Diffusers and humidifiers are designed for different purposes but use a lot of the same methods and components to achieve them. 

And while a diffuser does actually humidify a space, it is not particularly effective. Moreover, the diffuser does not have nearly as many features or capabilities as a proper humidifier. 

On the other hand, most humidifiers cannot be used with essential oils. In fact, you could damage the internal components of a humidifier by putting essential oils in it. 

Still, there are some specific models of humidifiers that come with an ‘aroma tray’ and an aromatherapy function. Even here, you should never put essential oils directly in the water tank of your humidifier. 

And finally, while there are a ton of alternative ways to increase relative humidity, the best, most effective, and most economical is still to use a humidifier.


Shawn Willis is all about humidifiers. After working for some of the biggest names in the industry, he started HumidifierGuys with Scott Dawson. Now, the dynamic duo helps others figure out what they need in their next humidifier.

Shawn is an avid sports fan, motorcycle enthusiast, and has two dogs named Whiskey and Boba.