We spent more than three weeks testing 13 diffusers, and our favorite is the Urpower 300ml Aroma Essential Oil Diffuser. It has nearly three times the capacity of most other options at its price, and it has the same clean design as diffusers that cost more than five times as much. It will change the ambience of any room, with light in multiple colors, mist, and a subtle scent.
The Urpower 300ml Aroma Essential Oil Diffuser is a simple white plastic cylinder in a field crowded with funny shapes and (very) faux wood. It’s also one of the least expensive diffusers we looked at, working and looking more or less the same as models four or five times the price. The medium-size tank provides water for seven hours of a strong stream of mist (though you’ll need to add more oil during that time for continued scent). It lights up in seven colors, offers a timer function, and has LED indicator lights that aren’t as distractingly bright as those on the competition.
*At the time of publishing, the price was $18.
If our top pick is sold out, consider the Urpower Essential Oil Diffuser 120ml Aromatherapy Diffuser. The design is relatively subtle, but the stream of mist is much weaker, and we don’t like the sloped top as much as the flat top on our main pick. The tank is smaller, so you’ll have to refill it more often than our top pick; it runs for three hours continuously or six if you set it to mist intermittently, so it’s a good option if you want something that will run for shorter amounts of time. We like the buttons better than those on our top pick, because they don’t beep. The Urpower 120ml also doesn’t beep when it shuts off. Though the manufacturer says this model works better in a smaller room, we found that adding more oil made it just as suitable for larger rooms as the Urpower 300ml.
If you want a device that does the best possible job of dispersing scent to multiple rooms at once and you don’t mind spending more money, the Organic Aromas Raindrop 2.0 Nebulizing Essential Oil Diffuser mists pure oil, unlike ultrasonic water misters. The lights on this nebulizer are dim compared with those on our top pick and runner-up, and there’s no cool mist to stare at. It’s less expensive than others of its kind, prettier, and far quieter (nebulizers typically make very loud grinding or buzzing sounds). It has a wood base, a glass stem, and an LED light that changes colors or can be turned off. The Raindrop runs for two hours, dispersing oil intermittently during that time. We found that the automatic shutoff was a nice way to avoid overdoing the smell; one cycle was typically enough to make a room plenty fragrant. If it isn’t enough for you, a quick twist of a knob starts another cycle.
I read and viewed dozens of blog posts, reviews, and YouTube videos to get up to speed on the available kinds of diffusers and brands, and I tested 13 different diffusers and nebulizers. I checked in with John Holecek, a physicist and author of our humidifier guide, to understand how airborne oil spreads, as well as with Nena Bowman, a poison-control expert, to discuss the risk of kids getting into your essential-oil stash.
If you want your place to smell nicer, a diffuser is a solid alternative to candles. Since a diffuser can’t catch fire, you can leave it on in one room while you’re in another, or while you’re sleeping. Unlike with candles or more passive scent dispensers like Glade PlugIns, you can vary the scent just by choosing a different oil. A diffuser will also make any bath feel a little fancier.
Diffusers do come with a few annoyances: Unlike candles, diffusers take a couple of minutes to set up, and they need cleaning every few uses.
While researching this guide, I saw blog post after blog post—often on sites that had the word wellness in their name—about what essential oils can do for your health. But there’s little scientific evidence to back those claims up. Berkeley Wellness, a rare “wellness” site that relies on peer-reviewed research and is edited by an MD, has a good summary of what researchers do and don’t know. We can recommend diffusers here only for their ambience, not their aromatherapy capabilities. An essential oil diffuser should never, ever be a replacement for medical care.
Search for “essential oil diffuser” on Amazon, and you’ll get pages upon pages of devices that are all slight variations of one another—many with buttons that look identical. The company that makes our top pick even confirmed that some of the manufacturers get their diffuser parts from the same place.
All of these diffusers will do the basic job of making a room smell nice. But pick one at random, and it might be too small, produce a weak stream of mist, clash with your decor, or have buttons that are confusing to operate.
Before we get to those details, though, we need to note the different kinds of diffusers—ultrasonic diffusers, which require water and produce a more subtle scent, and nebulizers, which don’t require water and produce a stronger smell.
The most popular electronic diffusers are ultrasonic diffusers. Such models have a small tank of water to which you add a few drops of essential oil, or more if you prefer a stronger smell. A vibrating diaphragm in the diffuser turns the water and oil into fine, cool mist (like boiling, but with force). The process produces a soft whirring noise, though it’s hard to hear unless you have your ear to the device. These diffusers start at $20 and work best in a single room. Because they light up and produce a stream of mist, they are nice to look at. The scent they produce is subtle compared with that of nebulizers, or even your average scented candle. (Smell is subjective, so we can discuss it only in relative terms: What I found to be a subtle peppermint scent, for example, had my boyfriend complaining and turning the device off when I was in another room.)
Many ultrasonic diffusers have a plastic fake-wood design that looks terrible in person. We think most people will prefer the other prevalent option, which is a plain, semitranslucent white plastic. The ones made of real wood are pricier and typically don’t light up in a range of colors, a feature we like.
We looked for an ultrasonic diffuser with a simple shape, and features such as a clearly marked fill line (if you overfill the tank, the device can’t produce a strong stream of mist), a lid that clicks into the base (rather than just sitting on top) so you can move it around without spilling, and buttons that don’t beep when you push them.
Ultrasonic diffuser tank sizes range from 100 to 500 milliliters; the best diffusers balance the benefits of a bigger size with a small footprint. Generally, the larger the tank, the thicker the mist, and the longer it can run without needing more water (although, since oil floats on water, the running time will be front-loaded with more scent). Despite what manufacturers say, a larger diffuser doesn’t really work better for a larger room—you just need to increase the amount of oil that’s being diffused.
Many medium-size and large diffusers have a timer option, so they will turn off after one or a few hours. This function allows you to run the diffuser several times without refilling the water (you should empty and wipe out your diffuser every few days if you’re not using up all the water). Smaller diffusers often have an option for intermittent diffusing, where they mist or spray oil for a set amount of time and then rest for a set amount of time; this pattern keeps the diffuser going longer on a single fill. Both of these features are nice, but not necessary.
Ultrasonic diffusers are not humidifiers, though companies sometimes advertise them as such. If you were to run (and refill) one continuously, it would distribute around 1,000 mL of water over 24 hours. In contrast, our pick for the best humidifier puts 3,785 mL of water in the air over the same amount of time without intervention.
Diffuser quality can vary widely even between models that look identical. Before you’re lured to a diffuser by glowing Amazon reviews, run the URL through Fakespot. That site gives many diffusers poor marks for having reviews that are suspiciously positive. We kept everything that had a C or above in the running for testing.
If you want a stronger smell and can spend more money, consider a nebulizer, which diffuses oil directly by blowing compressed air through it to turn it to mist. These models cost about $100, can be loud, and aren’t as interesting to look at, but they produce a more concentrated smell.
Some nebulizers have a wood base with a glass stem that lights up—they’re nicer-looking, though easier to break. In some cases you can’t turn the light off (the product description or photo should mention a “light” button). Other models have a bottle attached to a nozzle that sprays, usually concealed in a plastic or metal case.
All nebulizers feature some way to control the size of the stream of mist, usually a knob on the nozzle. All of them diffuse oil intermittently, since a constant stream of pure oil is powerfully smelly. On some, you can specify the length of the spritz time (say, 20 seconds) and the amount of time in between, but this level of control isn’t really necessary. It’s not uncommon for nebulizers to have a set amount of time that they run for at intervals; two hours is typical.
Don’t pay attention to claims from natural-health proponents that diffusing essential oils can help you breathe easier. In fact, if you have asthma or trouble breathing, you should exercise a little caution when diffusing essential oils in your home. (Ultrasonic diffusers might be the better choice, as you can easily control how much oil they disperse.)
No studies explicitly look at the effect of using an essential oil diffuser on symptoms of asthma, write experts on the American Academy of Allergy Asthma & Immunology’s website. But several oils have been shown to release compounds that have, in other studies, been associated with aggravating breathing troubles. In addition, “anecdotally, there have been reports of respiratory symptoms in asthmatics and non-asthmatics due to a variety of diffused essential oils,” the AAAAI experts write.
Be mindful of where you store your essential oils if you have anyone in your household who could possibly mistake them for a beverage or snack. Like many household products, they can be harmful in a high enough dose, and their bottles don’t have childproof caps, but they smell good enough that kids might assume they are also tasty.
Certain oils like wintergreen, camphor, and tea tree can be harmful to small bodies if they ingest as little as a teaspoon, according to Berkeley Wellness. In one case, 4 mL of wintergreen proved fatal. And ingesting citrus and cinnamon oil can cause painful irritation, said Nena Bowman, the managing director of the Tennessee Poison Center.
If a kid does get into a bottle of oil or a diffuser, don’t hesitate to call poison control, Bowman told us. “No question is ever a dumb question.”
I spent three weeks using a selection of ultrasonic diffusers and nebulizers around my apartment. I quickly eliminated a few for having undesirable design elements, like taking up a lot of space or having buttons that I found impossible to navigate without looking at the manual.
To discover everything that could possibly be annoying about a diffuser design, I rotated them through every location I could think of: kitchen counter, living room next to the litter box, guest room, bookshelf, coffee table in my bedroom while I slept, atop the toilet tank. I also used the diffusers at night, in a dark room, to see how bright the LED indicator lights were.
I paid attention to the noise level from nebulizers. When any nebulizer is on full blast, it produces a buzzing sound. The best ones allow you to turn them down so that this sound becomes nearly inaudible (but that makes the stream of mist weaker, too).
The Urpower 300ml Aroma Essential Oil Diffuser runs for longer and produces a stronger stream of mist than anything available at the same price; it can go for nearly seven hours on a single fill. It has a clean and simple design, unlike many other units we looked at. It lights up in seven colors and has LED indicator lights that aren’t too bright or annoying. Plus, it’s pretty quiet. While you can get an equally strong diffuser with a sleeker appearance for more money, we think most people will be pleased with the Urpower 300ml.
The 300-milliliter tank is three times the size of those in most other diffusers at the same price, allowing this model to continually produce mist for over twice as long. In addition to the ability to run until it’s empty (and then automatically shut off), the diffuser has three timer options to run for one, two, or three hours.
You get seven options for light colors and two brightnesses for each color, as well as the option of no light. The small yellow-green LED indicator next to the mist button sticks out less than the red and green light on several of the other units we considered.
This model’s cylindrical white plastic design was one of our favorites in a field filled with strange shapes and very fake plastic wood. It doesn’t draw attention to itself, and it’s easy to wipe out with a damp cloth between uses.
The top of the diffuser snaps snugly into the base, so you can pick up or rotate the whole diffuser by the lid. This design also makes it a little harder for kids to open the diffuser and mess with the water.
We had the following problem with nearly every ultrasonic diffuser we looked at: Since the device has just two buttons, you don’t get a simple on/off switch for the mist or for the lights; you have to cycle through every option to shut off either function. On the Urpower 300ml, this design is particularly annoying for the light, since you have so many options. The buttons beep when you press them, and you have to hold down the mist button for a second before the stream of mist begins. I found this annoying at first, but after I knew the trick it wasn’t an issue.
The Urpower 300ml also makes a beep sound when it shuts off. If you want to fall asleep while using this diffuser and are a very light sleeper, it might be too loud, as it was for this Amazon reviewer.
The lid can be a little tricky to get on and off the base for some people. “The lid fits over the base with water just fine but once you have it on it takes a bit more force than I think it should to try to get the arrows to line up at the bottom,” one reviewer writes. Still, we prefer a lid that secures to one that just rests on top, as was the case with some of the competition.
A diffuser with a matte plastic finish or one made from real wood might look a little nicer, especially when not in use. But to get one with a comparable stream of mist, you’d have to pay about three times as much.
*At the time of publishing, the price was $18.
If our top pick is sold out, or you’d like a diffuser that doesn’t beep when it shuts off, consider the Urpower Essential Oil Diffuser 120ml Aromatherapy Diffuser. The design is still simple compared with much of the competition, and it’s easy to use and clean. Like our top pick, it lights up in seven colors. While the Urpower 120ml doesn’t run as long as our main pick, it does cost half as much as many other diffusers its size.
The Urpower 120ml runs for three hours on the continuous-mist setting or six hours on the intermittent setting (30 seconds on, 30 seconds off). While our top pick doesn’t have an intermittent-mist feature, this model lacks a timer setting; it will always run until it’s out of water.
While the manufacturer’s instructions say that this diffuser works for a room that’s smaller than what our top pick can handle, we found that when we added more oil, the Urpower 120ml could make a larger room smell nice.
We like that the buttons don’t beep when you push them. But the mist button has an indicator light that’s green or red (depending on the mist setting), which we found unsightly compared with the yellow-green indicator on our top pick.
If you are willing to spend more money and are more focused on scenting your place with essential oils without the ambience-enhancing features of a diffuser, we like the Organic Aromas Raindrop 2.0 Nebulizing Essential Oil Diffuser. Of the five nebulizers we tested (which were all great at diffusing), it’s by far our favorite for aesthetic reasons. On low settings it’s just as quiet as an ultrasonic diffuser (most nebulizers are loud), and it’s the prettiest diffuser we tested overall. Unlike other nebulizers, it has neither a ton of buttons to mess with nor too few options to control your experience.
This diffuser is strong, and capable of dispersing enough scent to fill a whole apartment. It runs intermittently for two hours on about 20 drops of oil. The Raindrop 2.0 disperses oil for two minutes and then turns off for one minute; while some other nebulizers offer the option to customize the length of their puffs, we didn’t find that necessary, since we could still adjust their strength. If you want the Raindrop 2.0 to run longer, you have to reset it, but two hours should be long enough to scent a room and have the fragrance last a bit. While other nebulizers can run until you shut them off, we found them noisier and more expensive.
The Raindrop 2.0 has a dial to control the amount of mist that comes out. And while the diffuser does make noise, it’s not very loud unless you have it misting on full blast. You’ll need to clean it about once a week (and between oil if you’re using thick oils like sandalwood). That’s more cleaning than nebulizers with fewer glass parts would require, but we think the appearance, price, and low noise levels of the Raindrop 2.0 more than make up for the chore.
The Raindrop 2.0 comes with either an opaque black base or a wood base, with a grippy material on the bottom to keep it stable. In our tests, the touch-sensitive button to turn the light on and off was too easy to press by mistake when we turned the device on, and sometimes it took a couple of taps to turn off. This was annoying, but not a dealbreaker.
The fine mist this diffuser sprays might get on whatever you have sitting nearby, as one Amazon reviewer notes, so make sure to put nothing near it that you can’t wipe down.
We can name several other diffusers that we’d buy if we preferred their appearance over that of our top picks, or if we really wanted a feature (like intermittent diffusing) that a similar pick lacked. (Unless otherwise noted, these are ultrasonic diffusers.)
Of all the diffusers we looked at, the 100 mL Stadler Form Mia Aroma Diffuser is the most understated and design-conscious, with a matte finish, no mood light, and just one button. Next to the competition, however, it offers a weak stream: This diffuser takes a while to disperse oil, and sometimes it’s hard to see the mist at all, which makes it less visually interesting.
The Stadler Form Jasmine is the bulkier version of the Mia and comes in more colors. It has an option to run in intervals, 10 minutes on and 20 minutes off, for 24 hours. We didn’t test it because it’s pricey for an ultrasonic diffuser, without offering a lot more than the Mia. Also, one Amazon reviewer notes that the LEDs are strong: “Wow the lights are like a lighthouse beacon in the night.”
We like that the Now Solutions Real Bamboo Ultrasonic Oil Diffuser is made of real wood. Plus, at this writing, Fakespot gives the Amazon reviews a B, uncommon among diffusers. It has an option for intermittent diffusing as well as a timer—a combination that we didn’t see on any other ultrasonic diffuser. It’s expensive for an ultrasonic diffuser, though, and it doesn’t come in different color options.
We liked the symmetrical shape of the Anjou Essential Oil Diffuser, as well as its large size and unique pyramid design. However, several slightly annoying attributes together disqualified the Anjou early in our testing: The water reservoir is shallow, so the device takes up more space on a shelf or nightstand than the other 300 mL diffusers we looked at; the buttons make a beeping sound when you press them; and the faux-wood finish on the bottom is more likely to clash with decorating schemes.
The InnoGear 200ml Wood Grain Aromatherapy Essential Oil Diffuser has most of the same problems as the Anjou diffuser, including a large footprint and buttons that beep. (In fact, the bases of the two diffusers are nearly identical.) The fill line isn’t clearly marked inside, either, and the unit is made of faux-wood plastic.
Though they are slightly different shapes, the InnoGear Aromatherapy Essential Oil Diffuser is functionally identical to our runner-up pick, the Urpower 120ml. But this model costs a couple dollars more and has a slightly smaller tank.
Of all the diffusers we considered, the Diffuser World Aroma-Ace, a nebulizer, is the most industrial-looking: no wood (real or fake), no colorful lights. In our tests it was also louder than anything else we looked at, by far, emitting a grinding, buzzing sound as it dispersed oil—it sounded kind of like a refrigerator with a worn-out compressor. (Diffuser World sells a “silencer” attachment that is supposed to dampen the sound, but we found it didn’t work that well.)
The Aroma-Ace does have one of the best timers: You can adjust the amount of time it sprays oil, as well as the amount of time it rests (between a few seconds and 20 minutes). As with the other nebulizers we saw, you can adjust the amount of oil it sprays, too. Unlike many nebulizers, the Aroma-Ace comes with two atomizers, so you can switch oils without having to clean the system. The unattractive design also doesn’t seem as easy to break as the glass nebulizers we tested.
With the Diffuser World Aroma-Express, another nebulizer, you have no option to diffuse oil intermittently, which we found to be an important feature for nebulizers. This model is also an industrial-looking device, and in our tests it made a grinding noise as it ran. That said, if you’re looking for a nebulizer that doesn’t include any glass components, this one is effective, and it’s less expensive than your other options.
The Diffuser World Aroma-Infinity nebulizer is similar to the Aroma-Express but has an option to diffuse the oils intermittently. The sound it made in our tests was higher pitched and softer. However, we don’t think these features are worth the price tag for most people.
And here’s the competition we wouldn’t buy:
The Muji Ultrasonic Aroma Diffuser from the popular Japanese retailer Muji costs more than the competition yet doesn’t offer any clear benefits. Muji’s diffusers are similar in design to many of the inexpensive models we looked at, though they don’t give you the option to change the light to a different color. After a quick visit to a Muji store to see these in person, we dismissed them.
The InnoGear 500ml Aromatherapy Essential Oil Diffuser is one of the largest out there, and seems to mimic the design of the large Muji diffuser. It comes at a great price, but we’re skeptical about the positive customer reviews since Fakespot gives them a D grade currently. It also has a very large footprint at 168 mm, or 6.6 inches.
The Meco 300ml Aroma Essential Oil Diffuser appears to be identical to our top pick, but Fakespot gives the quality of the reviews an F at this writing, noting, “Our engine has profiled the reviewer patterns and has determined that there is high deception involved.” Therefore, we didn’t test it.
We were intrigued by the round, pebble-like shape of the BlueFire Electric Ultrasonic Humidifier Aroma Diffuser, but it was the most difficult to use of everything we tested, and the only ultrasonic diffuser for which we had to consult the instruction manual. It has two layers of plastic that you need to remove to fill the water tank, and the buttons are located on the back next to the cord and aren’t clearly marked.
The Joly Joy Wood Essential Oil Diffuser is one of the few ultrasonic diffusers made of real wood that we saw, but it’s about twice the price of our pick. Also, currently Fakespot gives a D grade to the Amazon reviews, which are not that great to begin with.
We tested the Welledia Pleasant Essential Oil Glass Nebulizing Diffuser with Bamboo Base and Color LEDs because it’s one of the nicer-looking nebulizers available. However, the LED can’t be turned off, something we didn’t realize until we ordered it. This model was a lot louder than the Raindrop 2.0 in our tests, making a buzzing noise as it diffused.
Manufacturers often recommend cleaning out ultrasonic diffusers once every few days or uses so that oils don’t build up and nothing can grow in the stagnant water. The maintenance instructions for our top pick recommend using a little fragrance-free dish soap (our top pick for dish soap fits the bill). To get it really clean, Essential Oil Haven suggests running it in a well-ventilated space for a few minutes with water and a few drops of white vinegar every so often. If you’re switching oils between uses, wipe out the diffuser with a damp cloth.
The maintenance instructions for our favorite nebulizer recommend cleaning the device with rubbing alcohol once a week, or immediately after running it with a thick oil like sandalwood. If you’re switching oils, clean it in between uses. Every once in a while, soak it in hot water with dish detergent to get it really clean.
One more note on the topic of cleanliness: We used tap water while testing the ultrasonic diffusers, even though many people and some companies suggest using distilled water because the minerals in tap water get propelled into the air along with your oil. The EPA says that it’s perfectly safe (PDF) to use tap water in an ultrasonic humidifier (which puts a lot more water into the air than a diffuser). As we note in our humidifier guide, however, tap water can produce a fine, white dust near the device. I did not notice this dust during diffuser testing—again, diffusers are much, much smaller than humidifiers.
(Photos by Michael Hession.)
Should we open another bottle of wine?