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How we found the best essential oil diffusers

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How we found the best essential oil diffusers

October 10, 2017

How we found the best essential oil diffusers

We spent more than 40 hours researching essential oil diffusers in order to find the best products to test. We started off by looking at the biggest brands in the category (such as dōTERRA), then expanded our search through subreddits liker/aromatherapy and r/essentialoils.

We also read through several essential oil and aromatherapy Internet forums, read studies and articles about the benefits of essential oils and diffusing those oils, and read about the diffusers that industry experts recommended.

Once we knew what to look for, we narrowed our search with a few more criteria:

  • Automatic shutoff
  • Operating time should be at least 2 hours, but ideally closer to 4 or 6 (or longer)
  • A water capacity of at least 120ml — however more is better
  • A manufacturer’s warranty

From there, we factored in positive reviews on Amazon and by professional reviewers as well as several interviews with brand representatives to determine which products we should test in-house.

We narrowed our list of finalists to the following:

The seven best essential oil diffusers

What exactly is an essential oil diffuser?

There are several different types of essential oil diffusers on the market. For this article, we focused on ultrasonic diffusers. Based on our research, ultrasonic diffusers are best for diffusing essential oils because they do not utilize heat in the production of vapor. Since heat can have a negative effect on essential oils, ultrasonic diffusers are the best way to get the full benefit of diffusing essential oils.

Ultrasonic diffusers work by vibrating the water in such a way that it vaporizes into the air. Since the essential oils are mixed into the water, they are carried along with the water. Ultrasonic diffusers generate the vapor without any heat, which best preserves the integrity of the essential oil.

Diffusers are better than any scented candle, because you can put more than 100 different essential oils into them. You can even combine two or more essential oils to create a unique blend.

The difference between a diffuser and a humidifier

While a diffuser does add a small amount of humidity into the air, it still functions notably different when compared to a humidifier.

A humidifier’s primary function is (unsurprisingly) to add humidity into the air. To do this, it utilizes a relatively large tank of water (typically measured in gallons) which is then heated and released into the air.

An essential oil diffuser has a much smaller tank of water, usually somewhere between 80ml to 350ml. This means that the humidifying effects of a diffuser are relatively minimal when compared to a humidifier. However, a diffuser is significantly better at getting essential oils into the air. In fact, usually it is not cost-effective to use a humidifier to diffuse oils at all.

For those who want aromatherapy benefits and humidity, it is best to use an essential oil diffuser and a humidifier.

Benefits of essential oils

Essential oils have been used for thousands of years, from cultures as far-reaching as Ancient Egypt and India. These oils have been used for a variety of purposes, from spiritual to medicinal, and there are a significant number of modern scientific studiesthat support the theory that essential oils can be beneficial in a number of very real and quantifiable ways.

The following are just a few examples of the types of benefits that essential oils can provide:


Eucalyptus has been used across many cultures and is often used in over-the-counter medications. When placed near the sinuses or on the chest it helps with congestion and sore muscles. Eucalyptus is particularly useful for diffusers like the ones we are testing — especially when used for congestion.


Lavender is typically used for bruises, cuts, and skin irritation. Studies also show that the scent can reduce levels of the stress hormone cortisol. Application on the skin has its uses, however lavender is popular for diffusers because it can create a soothing, relaxing scent in a room.


Used in many OTC remedies, peppermint can also be used as an essential oil in tea or other beverages, and also as a way to soothe the stomach. Studies show that peppermint increases oxygen levels in the blood, and can help a person be more aware.


Tea tree oil is commonly used directly on the skin, and can be used for everything from acne to fungal infections.


There are literally hundreds of essential oils to choose from, some more useful than others. We recommend you do some research to find a few essential oils that will work best for you. In our article researching and testing essential oils, we discovered quality can greatly vary by brands. Proper use and selection are required to maintain safety and to properly enjoy the benefits of these oils.

Do you need an essential oil diffuser?

A surprisingly small number of people actually know what an essential oil diffuser is. When we conducted a poll, only about half knew what an essential oil diffuser was.

That said, essential oil diffusers are quickly gaining popularity due to a growing interest in the health benefits of essential oils, as well as the fact that scented candles are not as safe as many once thought.

Research on the dangers of scented candles

There is a growing body of research which indicates that scented candles are not as safe as many think. In fact, many candles release harmful metals and compounds into the air — including lead, acetaldehyde, and formaldehyde.

While there are scented candles that do not release these harmful chemicals, asignificant number do. This issue has underscored the value and importance of finding alternatives to candles.

If you currently use scented candles for anything from aromatherapy to ambiance, it is imperative that you research your brand of candle to ensure it does not contain chemicals that could be harmful to you or your family.

A better option would be to switch over to an essential oil diffuser, which provides the same benefits as a scented candle, but uses natural ingredients — many of which have been proven over thousands of years.

The health benefits of essential oil diffusers

For many essential oils, there are different benefits attributed to applying them directly on the skin, versus having them diffused into the air. Some essential oils shouldn’t be placed directly on the skin at all.

Essential oils serve a number of purposes, including the following:


Essential oils are used for everything from relaxation (lavender) to pain relief (rosemary) to decongestants (peppermint and eucalyptus). By diffusing these oils into the air, you can gain the benefits for hours without needing to reapply the oils onto your skin.


There’s a reason why many spas have a distinctive smell — they’re using essential oils! Oils such as tea tree oil have been used for centuries to create the ambiance of a calm, safe place.


Many people are already familiar with the fact that citronella is a useful mosquito repellant. However, there are lots of other essential oils that work as well — which is a good thing if you’re not a fan of the citronella scent!

Essential oils that act as insect repellants include:

  • Cedarwood and eucalyptus for fleas
  • Thyme, juniper, and rose geranium for ticks
  • Citronella and peppermint for mosquitos

Once again, it’s worth mentioning that while there are candles that can perform many of the same functions as the oils listed, essential oils (especially 100% pure oils) contain none of the harmful chemicals found in many scented candles currently on the market.

Essential oils vs. scented candles

Some people think that essential oils are out of their price range. After all, when people think “essential oils” they often image an expensive day spa. However,essential oils are in fact significantly less expensive than scented candles.

For the math enthusiasts, here’s a breakdown:

A 22-Ounce Yankee Candle costs about $27 on Amazon, and is rated for somewhere between 110 and 150 hours. If we take the high end (150), and divide by the cost ($27), we get a cost of 18 cents per hour.


This means that the product cost for an essential oil diffuser is 4.5% of what it would be for a scented candle. When put into the context that essential oils have health benefits and scented candles have potential health risks, the choice is easy — even when we account for the electricity costs of a diffuser.

Important features to consider

There are a lot of essential oil diffusers available online. In fact, there are more than 32,000 essential oil diffusers available on Amazon alone. With so many products to choose from, narrowing the field to a few finalists can feel overwhelming. That’s why it’s important to filter for only the best quality and best value diffusers.

First, you want to determine the size of the room you want your diffuser to effectively cover. Most (high-quality) diffusers include an estimated room size they are most effective in.

Since “too much” diffusing is not a common problem with essential oil diffusers, and since many diffusers offer a way to reduce output if necessary, you should be much more interested in which diffusers provide sufficient coverage.

It’s also important to look at the water capacity of a diffuser, along with the estimated operating time. The operating time informs you of how long you can expect the essential oil scent to last in the room, while you can estimate the amount of water (and oil) diffused by taking the water capacity and dividing it by the operating time (e.g. 100ml and 2 hours would mean 50ml diffused per hour).

It’s also important to take into consideration the build quality of the diffuser you buy. Essential oils can be corrosive to some plastics, which means that a cheaply-made diffuser might break down after only a few months of use. All high-quality diffusers use polypropylene, or another strengthened polymer or material, to ensure the longevity of the product.

Ease of use is another important consideration. This includes both setup (which should involve little more than putting water and your preferred essential oil into the diffuser) and clean up.

The size, or dimensions of a diffuser might not matter to everyone. However, for those with limited space, it might be worth looking into a diffuser with a smaller footprint. Similarly, a noisy diffuser can be distracting in an otherwise-quiet setting — such as a yoga studio or even your bedroom.

Features such as a timer and ambient lighting can be a nice touch, and are worth taking into consideration when comparing one diffuser to another.

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