Humidifier Vs Diffuser: See the Differences

By Samuel-N •  Updated: 06/15/22 •  11 min read

Diffusers and humidifiers are both designed to freshen the air in your home. A diffuser does this by adding the desired aroma to the air, while a humidifier adds moisture to the air, helping dry combat air.

These two devices are often mistaken to be the same or taken to work similarly. So, is a diffuser different from a humidifier? This article will explore these two home appliances, giving you a better understanding of how they work, their pros and cons, and their differences.

What is a Diffuser?

A diffuser is an electrical appliance designed to expel essential oils or other aromatic plant compounds into the air. Diffusers are a great way to get your house smelling good with the added benefit of enhancing physical and emotional health.


Diffusers come in different types, shapes, and sizes. There are four different types of diffusers available in the market. These are nebulizing, ultrasonic, heat, and evaporative diffusers.

Diffuser Working Mechanism

There are different ways a diffuser can help create a custom environment in your home, workspace, or office. However, choosing your preferred diffuser type should be influenced by the working mechanism of a diffuser.

At the basic level, a diffuser has one goal, i.e., breaking down the compounds in your favorite essential oils and expelling them into the air for your benefit. However, given the four choices of diffusers available, how do you know which is right for you. Below is a summary breakdown of how each of the diffusers works.

Types of Diffusers

1. Nebulizing Diffuser

A nebulizing diffuser works more similarly to a venturi pump. High-velocity air is blown on top of a tube, creating a vacuum effect that sucks the essential oils to the top of the tube and blows out the diffuser as a fine mist.

Nebulizing Diffuser

Nebulizing Diffuser

The working principle of a nebulizing diffuser does not alter the chemical composition or scent of essential oils, which brings the most benefits and thus makes it a favorite among many users.

2. Ultrasonic Diffuser

Ultrasonic diffusers are also called humidifying diffusers. Ultrasonic diffusers use water, essential oils, and electronic frequencies to create a fine mist. Water is added first, followed by essential oils.

When the diffuser is turned on, ultrasonic vibrations created by a disk inside the diffuser agitate the water causing the essential oils and water to break into tiny particles. The tiny particles are then dispersed into the air in mist. The process adds an aroma to the air while simultaneously humidifying the air.

3. Heat Diffuser

As the name suggests, heat diffusers use heating properties on essential oils, which breaks up the essential oils (evaporation); thus, adding aroma into the air — heating essential oils using high heat causes a stronger smell. However, intense heating may alter the chemical composition of essential oils, which lessens the benefits.

A good heat diffuser will use very low heat on the essential oils; thus, it avoids drastically changing the chemical composition of the oil being diffused.

4. Evaporative Diffuser

An evaporative diffuser works by passing air through a diffuser filter or pad. Essential oils are added to the filter, and a fan blows air through it, which causes the essential oils to evaporate and spread around the room.

Another type of evaporative diffuser does not require a fan to blow air but instead uses air in the room to slowly diffuse essential oils around a small area. This working mechanism is normally used with personal diffusers like bracelets, pens, necklace pendants, or personal oil inhalers.

Pros of a Diffuser

Cons of a Diffuser

What is a Humidifier?

A humidifier is a machine that adds moisture to the air. It is a favorite household appliance among people who dread the air during winter time and for those living in dry climates. A humidifier will help a room increase or maintain a certain moisture level.


Humidifiers come in four main types; you can choose between them. The type of humidifier you choose depends on your budget, preferences, and the size of the area you want to add moisture to. The four types are evaporative, impeller, steam, and ultrasonic humidifiers.

Humidifier Working Mechanism

Just like diffusers, the working principle of a humidifier will depend on the type of humidifier you have. However, humidifiers have one main objective: to increase or maintain the humidity in your home/office to alleviate dryness. Below is a summary of how the four types of humidifiers work.

Types of Humidifiers

1. Evaporative/Wick Humidifier

Evaporative humidifiers sound just like evaporative diffusers. However, they work a little differently. The system uses a paper, cloth, or foam wick to draw water out of the water reservoir via capillarity. A fan then blows air over the wick aiding the air in absorbing moisture.

The higher the humidity in your home, the harder it becomes for water to evaporate from the wick; thus, this humidifier is self-regulating. When Humidity increases – Vapor output decreases.

2. Impeller Humidifier

Impeller humidifiers work by using a rotating disk called the impeller. The disc rotates at fast speeds, breaking water into fine droplets that come out as cold fog from the humidifier.

3. Steam Humidifier

Also referred to as a vaporizer, a steam humidifier uses heat to boil water and release it as steam into the room. Steam humidifiers are by far the simplest, cheapest, and most popular.

Steam humidifiers, however, should be used with caution because they can cause burns to the skin if not correctly handled.

4. Ultrasonic Humidifier

Just like an ultrasonic diffuser, ultrasonic humidifiers use a disk vibrating at an ultrasonic frequency. The mechanism creates water droplets that are released as a cool fog.

Pros of a Humidifier

Cons of a Humidifier

Humidifier Vs. Diffusers – The Differences

1. Humidifiers and Diffusers Have Different Purposes

Humidifiers are designed to maintain or increase the humidity and moisture of a room. On the other hand, diffusers add aroma to your home air by diffusing essential oils. Though some diffusers may add humidity to a room, they are ineffective compared to a humidifier, and you will hardly notice a humidity difference. Read about using essential oils in a humidifier.

2. Humidifiers Have Much Bigger Water Tanks

The size and capacity of water tanks are another striking difference between humidifiers and diffusers. Humidifiers have larger water tanks because they require a large capacity to hold enough water to increase and maintain humidity.

Diffusers, on the other hand, do not require large water tanks. Even ultrasonic diffusers that use water to diffuse essential oils into the air have small water tanks compared to humidifiers. On average, a humidifier will hold 3800ml compared to the diffuser, which will hold up to 500ml.

3. Some Diffusers Don’t Use water

Besides the ultrasonic diffuser, diffusers rarely use water to expel essential oils into the air. A nebulizing diffuser is a great example of a diffuser that does not use water. Because of its working principle, nebulizing diffusers give essential oils the best benefits.

4. Health Effects of Diffusers and Humidifiers

Both diffusers and humidifiers have their health effects. However, these health effects (negative ones) come about from using or handling these appliances in a way not intended. Diffusers, misused, might harm your pets or, even worse, your family members or you. Humidifiers can also be troublesome if they are not properly maintained.

Wrapping Up

Both diffusers and humidifiers have different working mechanisms and health benefits. If aromatherapy is not your primary concern, and you need to humidify the dry air in your home, then you require a humidifier. A diffuser will reap the health benefits of your favorite essential oils.

Are you still undecided about the two choices? There are devices in the market that humidify and also diffuse oils. These devices will be a great choice if you are having difficulty choosing between the two.


Samuel is the founder of Cozy Indoor and has been in the home renovations industry since 2013. Since then, his mission is to make home cooling, heating, and air quality easier for everyone to understand. Read my guides and reviews here on cozyindoor.