With more than 45 hours spent researching and testing the best essential oil diffusers on the market, we concluded that the Smiley Daisy Hibiscus Diffuser is the best option available. With a price point below $40, it performs better than other diffusers while still offering fantastic value. After several months of daily long-term testing, the Hibiscus continues to work as well as it did on day one, and we expect many more years of use out of this diffuser.
We also found that essential oil diffusers are a much safer and healthier alternative to scented candles, and are a fraction of the cost of scented candles when compared on a per hour basis.
Our Top Pick: The Smiley Daisy
A top performer across every category while still maintaining affordability, the Smiley Daisy is our pick for most people.
Table of Contents
- How we found the best essential oil diffusers
- The seven best essential oil diffusers
- What exactly is an essential oil diffuser?
- Benefits of essential oils
- Essential oils vs. scented candles
- Important features to consider
- How we tested
- The best essential oil diffuser
- The second-best diffuser
- Best all-day or all-night diffuser
- The other essential oil diffusers we considered
- The bottom line
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 like r/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
|Product||Run Time (min)||Water Capacity (mL)||Vapor Rate (mL/hour)|
|1. Smiley Daisy||6-7||350||50-58|
|2. dōTERRA -|
|3. PureSpa - Compact||7||100||14.3|
|4. Smiley Daisy -|
|5. ZAQ - Allay||4||80||20|
|6. Greenair - Spa Vapor+||4||150||37.5|
|7. PureSpa -|
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, the design of an ultrasonic humidifier is notably different.
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. Most ultrasonic humidifiers have water tanks that are not designed to hold essential oils (discoloration and cracking are common results of experimentation) and a humidifier uses far more energy than a diffuser.
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 studies that 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.
Lots of others
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, a significant 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.
The essential oil math is a little bit more complicated.
There are approximately 20 drops in a milliliter of Lavender essential oil, and 29.574 milliliters in an ounce. This comes out to about 591 drops per ounce.
A four ounce bottle of Lavender essential oil costs about $10.50 on Amazon, which means you can purchase 2,364 drops of Lavender essential oil for $10.50, at a cost of $0.0044 per drop.
Smiley Daisy recommends that we use about 3 drops of oil per 100ml, which means in the 350ml Hibiscus tank, we would need 10.5 drops, which we will round up to 11 drops. At $0.0044 per drop, those 11 drops cost $0.0484.
A 350ml tank lasts somewhere between 6 and 7 hours. If we estimate conservatively, that means the 11 drops will last 6 hours. Since the cost of the 11 drops is $0.0484, then the cost per hour is $0.0081 cents.
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.
How we tested
It’s one thing to look at a product page on Amazon, but it’s something entirely different to actually hold and use a diffuser. In order to determine the best aromatherapy diffuser on the market, we ordered our seven finalists and put them through a series of tests in our San Diego office.
The first thing we did was open the box and read the instruction manual.
Next, we looked at the pieces and assessed how easy it would be to set up the diffuser. We also took into consideration the build quality of the diffuser.
After that, we looked at the settings and options available on the diffuser, including auto-off, lighting, timers, etc. We also took note of how intuitive the controls were, and whether we needed to actually refer to the instruction manual more than once.
We also checked to confirm that the specs and features listed on each diffuser’s product page matched the product itself. Specifically, we checked ambient lighting, operating time, water capacity, timers, and automatic shutoff when the water reservoir is depleted. Fortunately, all seven finalists held up to expectations, so we moved on to differentiating between them with their performance as an actual diffuser.
Diffuser performance metrics
We don’t have a hermetically-sealed lab, so we needed to do some improvising when developing our tests. To test each of the diffusers, we closed the doors and windows in our conference room, which measures 21 by 10 by 12 feet, for a total of 2520 cubic feet and 210 square feet.
We then filled the first diffuser with water and the recommended number of drops of essential oil (we used sweet orange oil for our testing because it has a distinct and easily-detectable scent), making sure to use the same ratio of water to oil for each diffuser.
With the conference room closed off, we put the first diffuser at one end of our 8-foot conference table and calculated how long it took for the scent of the sweet orange oil to reach the other side of the table — with three judges to ensure as accurate a measurement as possible.
After measuring how long it took for the scent to reach the other side of the conference table, we left the room and let the diffuser run for 30 minutes with the doors and windows closed. We went into the room and touched the diffuser to determine if any parts were warm and hot, and also measured the noise level using a BAFX Products Decibel Meter.
After taking our measurements, we turned the diffuser off and closed the door, checking back in every few minutes to see how strongly the scent lingered in the room. After letting the room air out for at least a few hours we repeated this for each of the 7 finalists and quantified our data into the table below:
The best essential oil diffuser overall
While all seven of the diffusers we tested do a good job of releasing essential oils into the air, the Smiley Daisy Hibiscus Diffuser was easily the best of the pack. The diffuser’s short stature, coupled with strong build quality and four sturdy rubber feet means that this diffuser won’t get knocked over very easily.
What makes the Hibiscus really stand out is the vapor output it produces, as well as the quality of that output. The water capacity of the Hibiscus diffuser is 350ml, which is more than double the capacity of every other diffuser we tested. With a maximum run time of between 6 and 7 hours, this translates to approximately 55ml of vapor per hour.
The diffuser also produced a strong stream of vapor, which could be seen as much as 20 inches from the table (and about 16 inches above the spout on the diffuser) which, again, was higher than all the other finalists we tested.
The large capacity and strong vapor stream of the Hibiscus made a noticeable difference during our testing. We found that there was a strong scent — about as strong as when the diffuser was on — for about 15 minutes after we turned the diffuser off. The scent remained quite noticeable until the 30 minute mark, and a lingering scent remained until almost an hour after turning the diffuser off.
Operation of the Hibiscus diffuser is simple as well. The instruction manual has very straightforward instructions, and using the product feels intuitive right away. There are two separate buttons on the front of the diffuser — one for turning the diffuser on or off (including a setting for a 2 hour timer), and a separate button for turning on and off the light.
The light itself offers seven different color options, which can either cycle or be locked onto one color. The light itself isn’t particularly bright, so it could serve as an effective night light without disrupting sleep (especially if you choose the red light).
Finally, the Hibiscus essential oil diffuser runs extremely quietly. In our office, which measures about 40 decibels with the doors and windows closed, the diffuser only generated 46.5 decibels when the decibel meter was less than an inch away from it.
Smiley Daisy also offers a 180 day warranty, which ensures that, if you’re one of the unlucky few that get a defective product, you’ll be able to get a replacement at no cost and with no hassle.
Overall, the Smiley Daisy Hibiscus Essential Oil Diffuser offers impressive build quality and the best overall performance of the essential oil diffusers we tested. At a price point below $40, the diffuser is a great value as well.
- The Hibiscus has a strong build quality with sturdy rubber feet.
- It has double the water capacity of other diffusers we tested.
- The Hibiscus even cycling light options that can also act a night light.
What we didn’t like about the Hibiscus Diffuser
While the Hibiscus diffuser was our best pick, there were a couple of negatives about the product. The biggest potential problem is the large footprint of the diffuser. Unlike most diffusers, which utilize vertical space in their design (and particularly for their water reservoirs), the Hibiscus diffuser is short and wide, measuring 8.3 by 6.6 inches (and only 3.2 inches of vertical height).
In addition, the light generated is minimal, functioning more as a design element than an actual source of light.
All that said, these negatives are very minor when compared to the overall package that is the Hibiscus diffuser.
The second-best diffuser
The dōTERRA Petal Diffuser is another very strong option from our list of finalists. The build quality is excellent, with a simple two-piece design that is made even simpler by the fact that the top can be placed on the base piece in any direction. The materials feel strong and sturdy, and we expect that the Petal diffuser will stand the test of time.
The dōTERRA instruction manual stands out as well. In addition to offering simple and straightforward instructions, the manual also includes images of the diffuser from the top, side, and bottom, so that you know exactly what to do — no matter what language you speak!
During our testing, we also found that the Petal diffuser was able to reach the other side of our 8-foot conference table very quickly — the average our testers agreed upon was just 35 seconds. This is less than half the time that the Hibiscus diffused, and while not a particularly scientific testing method, it does say something significant about the dōTERRA diffuser’s ability to permeate a room quickly.
The light produced by the diffuser is a pleasant, soft white, and provides notably more light than the Hibiscus diffuser. However, the Petal diffuser is limited to only white light, as opposed to the Hibiscus’ 7 color options.
The Petal diffuser is very quiet as well. In our conference room, where ambient noise registered at 41 decibels, the Petal diffuser only generated 46 decibels when our noise meter was less than an inch away — comparable to the Hibiscus diffuser.
Similarly, the scent was quite noticeable for nearly 30 minutes after shutting off the diffuser (just like the Hibiscus), and the essential oil could still be smelled for about one hour after the diffuser was shut off.
Operation of the diffuser is simple. There are two buttons on the front, one for the light and the other for turning the diffuser on or off. One interesting feature we noticed was that the Petal Diffuser must have water in it before being turned on — however we consider this a safety feature that we are better off having.
Another strange feature we noticed was that the diffuser defaults to a 2 hour timer, and hitting the button again then cycles through the 1 and 4-hour settings before shutting off again. This is a minor quirk, but it did stand out to us during testing.
- The petal has a strong and sturdy build quality.
- The diffused scent from the petal permeates room quickly.
- The Petal has a soft white light that does not change color.
Where the dōTERRA Petal diffuser fell short
While we certainly like the dōTERRA diffuser, and would recommend it as a great option, there were a few areas in which it fell short of our top pick, the Smiley Daisy Hibiscus diffuser.
First off, the Petal diffuser does not come with a water pitcher. While this might seem to be a minor point, it does mean that you need to either use a pitcher of your own (not ideal because many pitchers don’t measure in milliliters), or you need to unplug the diffuser and bring it to the faucet — again, not ideal since you’re bringing electronics to a water source (not to mention it’s a bit inconvenient).
The Petal diffuser also produces less vapor than the Hibiscus. The Hibiscus has a 350ml tank, runs for around 7 hours, and produces an estimated 50ml of vapor per hour. The Petal diffuser, with its 150ml tank and 4 hour maximum runtime, produces an estimated 37.5ml of vapor per hour. This lower level of vapor produced is compounded by the fact that the Petal diffuser has a maximum runtime that is 2 hours shorter than the Hibiscus.
Finally, the dōTERRA Petal diffuser costs significantly more than the Hibiscus diffuser. While we were able to consistently price the Hibiscus around $37, the Petal diffuser was found at prices ranging from about $57 to as much as $70.
The bottom line is that the dōTERRA Petal diffuser is a great product, and is more compact than the Hibiscus diffuser. However, in an apples to apples comparison, the Hibiscus comes out ahead.
Best all-day or all-night diffuser
The Pure Enrichment – PureSpa Deluxe is a great product, and if we hadn’t also tested the Smiley Daisy Hibiscus and dōTERRA Petal diffusers, we would have been confident recommending it as our best pick.
The PureSpa Deluxe is a nice-looking product, made from high-quality materials and with an elegant polish and design that would fit in anywhere from a yoga studio to a corporate office. The 2-year manufacturer warranty provides both peace of mind and says a lot about the confidence that Pure Enrichment has in their diffuser.
What makes the PureSpa Deluxe really stand out is its 8 to 10 hour running time, which is notably longer than both of our top picks. This means you can turn the diffuser on at the beginning of your workday (or before going to sleep) and it will run consistently throughout the entire day (or night) without a second thought.
The lighting is also well-executed, with the option to cycle through blue, green, red, yellow, and purple — however there is not a setting to stay locked onto one color. Also, much like our top picks, the PureSpa Deluxe did not become hot anywhere, even after running continuously for 30 minutes.
First off, the water capacity of the PureSpa Deluxe is just 120ml, less than both the Hibiscus (350ml) and the Petal (150ml). That, coupled with the extended runtime of the PureSpa Deluxe means that the amount of vapor produced per hour is significantly lower than either of our top picks.
We calculated the vapor diffused by the PureSpa Deluxe per hour was around 12ml to 15ml. This stands in stark contrast to the Hibiscus (55ml per hour) and the Petal (37.5ml per hour).
If you want to diffuse for extended periods of time, there's no better choice than the PureSpa.
This difference was noticeable in our testing as well. After 30 minutes with the PureSpa Deluxe on, we found that the scent in the room was certainly present, but notably weaker than it was with either the Hibiscus or the Petal diffusers. Furthermore, the scent was all but gone 15 minutes after turning the diffuser off.
Finally, the PureSpa Deluxe is notably louder than both the Hibiscus and the Petal diffusers. Our noise meter detected 51 decibels, which is about 5 decibels louder than both of our top picks.
Ultimately, the PureSpa Deluxe is worth considering if you want a diffuser that can run all day without needing to be refilled, and if you are more interested in having a subtle scent of essential oil in a particular room.
- The PureSpa comes with a 2-year manufacturer warranty.
- The PureSpa has a longer running time than both of our top picks at 8 to 10 hours.
- The PureSpa is notably louder than Hibiscus and Petal diffusers.
The other essential oil diffusers we considered
While the three diffusers mentioned above are our best picks, the remaining four all performed well too. However, each of them had one or more aspects which took them out of contention for the top spots.
ZAQ Allay LiteMist Diffuser
The ZAQ Allay diffuser has one of the more creative designs of the diffusers we came across. The LED lighting looks great emanating from the long cap (which itself is available in multiple colors).
However, the diffuser itself only has a water capacity of 80ml, which with a maximum 4 hour runtime means that this diffuser only produces about 20ml of vapor per hour.
In addition, we noticed that the mist fell to the table — which indicates that this particular diffuser does not break the water into small enough particles to float through the room. This observation was backed up by the fact that the it took 2 minutes and 15 seconds for the scent of the essential oil to reach the other side of our 8-foot conference table.
Finally, the build quality of this diffuser, while not terrible, can’t really compete with several of the other products we tested. For the $40 price point, there are simply better options available.
Smiley Daisy Love in a Mist Diffuser
The intricate and Zen-like shapes etched into the porcelain make the Love in a Mist diffuser arguably the “prettiest” product we tested. The build quality of this diffuser is fantastic inside and out, with high-quality plastic for the interior reservoir. The Love in a Mist diffuser also has several lighting options, which can vary or remain locked onto one color choice.
However, during our testing it took 3 minutes and 15 seconds for the scent of the essential oil to reach the other side of the table — significantly longer than our best picks and well beyond any possible margin of error with that admittedly non-precise experiment. In addition, we detected 52 decibels of noise next to the diffuser, notably louder than our best picks.
While this is a beautiful diffuser, it is more expensive than the other products we tested (around $60) with less impressive results. However, if you are more concerned with beauty rather than peak performance, this is a compelling (and reasonably functional) option.
PureSpa Compact Diffuser
The PureSpa Compact diffuser is one of the most popular options on the market, with thousands of Amazon reviews averaging 4.6 stars. This diffuser is simple, easy to operate, and provides 7 hours of diffusing with 100ml of water. This diffuser also has ambient LED lighting, and is made from cheap but durable materials.
The most significant downside to this diffuser is the 100ml tank and 7 hour run time — which translates to a paltry 14.3ml of vapor per hour. This deficiency presented itself in the 2 minute and 30 seconds it took for the scent of the essential oil to reach the other side of the table.
Greenair Spa Vapor+
The Greenair Spa Vapor+ was the last diffuser we tested, and overall it is a decent product. With a 150ml tank and a 4 hour run time, this diffuser generates an impressive 37.5ml of vapor per hour.
However, this diffuser is on the noisier side, registering 52 decibels, and the scent of the essential oil disappeared soon after we turned off the diffuser (within 10 to 15 minutes). This fact, in conjunction with the considerable vapor production, signifies that the Spa Vapor+ is simply unable to produce vapor particles small enough to remain suspended in the air for extended periods of time.
Long-term testing notes
After about nine months of almost-daily use, both the Smiley Daisy Hibiscus and the dōTERRA Petal diffusers are still working great. One thing we noticed with the Hibiscus in particular was that the residual smell of essential oils builds up in the reservoir over time. This doesn’t have a huge impact, but can have an undesirable effect on some scents.
We were able to successfully remove the residual scents by cleaning the reservoir with a little dish soap, some warm water, and very light scrubbing with a paper tower. We don’t recommend using any cleaning products beyond dish soap and water because it could corrode the components of the reservoir itself.
The bottom line
All of the diffusers we tested can generate enough vapor to make a small to mid-sized room smell like the essential oil of your choice. However, some did better than others, especially when price is taken into account.
The Smiley Daisy Hibiscus Diffuser stole the show, generating lots of vapor and producing a long-lasting scent in our conference room. The Hibiscus diffuser also has excellent build quality, and its low center of gravity makes it a sturdy fixture on any flat surface.
The dōTERRA Petal Diffuser came in a close second, held back primarily by its price and its vapor production.
The rest of the options all have their pros and cons, but for the money the Smiley Daisy Hibiscus Diffuser provides the best value and the best performance across all the metrics we tested.