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We spent more than four weeks testing 17 diffusers, and our favorite is the Urpower 2nd Gen 300ml Aroma Essential Oil Diffuser.
It puts out a strong stream of mist, has a larger capacity and smaller footprint than much of the competition, and, while affordable, has a clean design that looks better than others at its price.
The Urpower produces a strong stream of mist, lasts longer between refills, looks better, costs less, and has a smaller footprint than similar competitors.
The Urpower 2nd Gen 300ml Aroma Essential Oil Diffuser is a simple white plastic cylinder in a field crowded with funny shapes and (very) faux wood. It’s one of the least expensive diffusers we looked at, working better than 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 much of the competition. It’s easy to wipe out with a cloth to keep clean.
Runner-up Asakuki 500ml Essential Oil DiffuserLarger size, longer runtime With as strong a stream of mist as our pick, this diffuser has a larger tank you won’t have to refill as often. However, it takes up more space, and the faux-wood look isn’t for everyone.Buying Options$26 from Amazon $36 from Walmart Urpower 500ml Aromatherapy Essential Oil DiffuserAn equal 500 mL option This 500 mL model is nearly identical to the Asakuki.Buying Options$26 from Amazon
With as strong a stream of mist as our pick, this diffuser has a larger tank you won’t have to refill as often. However, it takes up more space, and the faux-wood look isn’t for everyone.
This 500 mL model is nearly identical to the Asakuki.
If our top pick is sold out or you’d like a slightly bigger tank, we recommend the Asakuki 500ml Essential Oil Diffuser (or the nearly identical Urpower 500ml Aromatherapy Essential Oil Diffuser). We recommend whichever you prefer on price or aesthetics, and both have a strong, rich, stream of mist that’s on par with that of our pick. At around double the tank size of our pick, 500 mL diffusers requires fewer refills—and in fact, these diffusers are the only style we tested with a unique low-output mode that can run for up to 16 hours. However, a model at this size also takes up more space. They both have a faux-wood base, which some people will find a little tacky. Both light up in seven colors, have a timer similar to our pick’s, and are easy to wipe out between uses.
This compact model is the most attractive diffuser we recommend, but its smaller tank doesn’t last as long and its stream of mist isn’t as powerful as our pick’s. It’s also far pricier.
If you’d prefer a diffuser that looks a little nicer and don’t need to diffuse scent in a large space, we like the Vitruvi Stone Diffuser. With a porcelain shell in a few neutral colors, it’s the only stylish diffuser we tried that both features a strong stream of mist and is easy to use. It’s one of the only diffusers we tested with a truly subtle indicator light (positioned on the back of the unit), making it the best choice if you’d like it to run while you’re sleeping in a dark room. The tank is on the small side, so you’ll have to refill more often, and while it’s easy to wipe out, two layers of lid make cleaning and refilling slightly more annoying than with our top picks. It’s also pricier (but could make a better gift).
If your top priority is a strong smell, go with a nebulizer. It’s pricier than our top pick and harder than ultrasonic models to clean, but unbeatable at filling a room (or a few) with scent.
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 is a nebulizer that mists pure oil, unlike our other picks, which are ultrasonic. (Here’s a detailed explanation of the difference.) The lights on this diffuser 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). The Raindrop runs for two hours, dispersing oil intermittently, and an automatic shutoff helps avoid overdoing the smell. Like all nebulizers, it’s annoying to clean.
Essential oils can be toxic to pets. Don’t apply any directly to an animal’s skin, and avoid using an active diffuser in the same room as your pets.
The Urpower produces a strong stream of mist, lasts longer between refills, looks better, costs less, and has a smaller footprint than similar competitors.
With as strong a stream of mist as our pick, this diffuser has a larger tank you won’t have to refill as often. However, it takes up more space, and the faux-wood look isn’t for everyone.
This 500 mL model is nearly identical to the Asakuki.
This compact model is the most attractive diffuser we recommend, but its smaller tank doesn’t last as long and its stream of mist isn’t as powerful as our pick’s. It’s also far pricier.
If your top priority is a strong smell, go with a nebulizer. It’s pricier than our top pick and harder than ultrasonic models to clean, but unbeatable at filling a room (or a few) with scent.
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 17 different diffusers and nebulizers. I checked in with John Holecek, a physicist and the original author of our humidifier guide, to understand how airborne oil spreads, as well as with Nena Bowman, the managing director of the Tennessee Poison Center, to discuss the risk of kids getting into your essential-oil stash. Wirecutter senior staff writer and resident pet expert Kaitlyn Wells spoke to experts about how to diffuse oils if you have furry family members (with caution!).
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 away or 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. But 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. And if you have small kids, pets, or respiratory problems, there are reasons to consider skipping a diffuser.
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. We recommend diffusers here only for their ambience, and an essential oil diffuser should never be a replacement for medical care.
For example: 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, be cautious. 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. “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.
If you have small children, a diffuser comes with additional considerations. Plan to store your essential oils out of reach, as they smell good enough that kids might assume they are also tasty. Many oil bottles lack childproof caps, and many oils can be harmful even if ingested in only small amounts. In one case, 4 mL of wintergreen proved almost fatal. And ingesting citrus and cinnamon oil can cause painful irritation, said Nena Bowman, the managing director of the Tennessee Poison Center.
Likewise, if you have pets, keep essential oils out of reach from them, too, and diffuse them with caution. While the biggest danger comes when owners apply oils to their pets (which you should not do at all), you’ll want to avoid putting certain oils in the air too. In the post “Are Essential Oils Safe for Pets?” Wirecutter senior staff writer and pet owner Kaitlyn Wells lists which specific oils to steer clear of. Experts she spoke to advised against using a diffuser in the same room as a pet, as the oil can settle on their fur. If you have a bird, skip the diffuser altogether: Birds’ lungs are sensitive.
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.
Despite the similarities among models, there are two distinctly different types of diffusers overall: Ultrasonic diffusers and nebulizers. Ultrasonic diffusers are the more popular type in part because they’re more affordable and they put out a more subtle scent, using a vibrating diaphragm to turn a solution of water and oil into fine, cool mist. Nebulizers, which diffuse concentrated oil by blowing compressed air through it to turn it to mist, produce a stronger smell, and they are less popular perhaps because they usually cost more and can make more noise.
One other thing to note about types: The word “ultrasonic” applies to some humidifiers as well, but oil diffusers are not humidifiers—even though diffuser manufacturers sometimes advertise them as such. If you were to run (and refill) an oil diffuser continuously, it would distribute around 1,000 mL of water over 24 hours. Good humidifiers (like our picks) have much larger tanks and humidity sensors that can distribute far more water over a longer period without needing to be refilled—and they are better able to maintain properly humidified air in your home.
We have picks of both types of oil diffuser, but the majority of our picks are ultrasonic, and the features you typically see on ultrasonic models guided our selection criteria. Here are the factors that set the best models apart, in order of importance:
With these criteria in mind, we shopped among hundreds of oil diffusers for sale at Amazon, Target, and Bed Bath and Beyond, and we also looked at niche retailers like Sephora, Madewell, and Anthropologie. We eliminated dozens of diffusers that didn’t meet our criteria and eliminated a few more (with glowing Amazon reviews) after running the URL through Fakespot, crossing off any with a Fakespot rating below a C. This left us with 13 diffusers to try firsthand in our first round of testing. For an update in 2018, we tested four additional diffusers, this time prioritizing diffusers that look nice.
I spent four weeks using a selection of ultrasonic diffusers and nebulizers around my apartment. We quickly eliminated a few for having undesirable design elements like taking up a lot of space or having buttons that we found impossible to navigate without looking at the manual.
We observed the diffusers running side by side to visually compare the size and height of the streams of mist, the key factors in how well they ought to distribute oils. Then, we ran the diffusers for several hours to confirm whether they effectively made the room smell like essential oils. (Scientifically measuring the exact effectiveness of each diffuser was beyond the scope of our review, but we found observing plume size and taking subjective notes on smell generally gave us a clear picture of which units worked better than others.)
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, atop the toilet tank, on a coffee table in my bedroom while I slept. 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 produces a strong stream of mist, lasts longer between refills, looks better, costs less, and has a smaller footprint than similar competitors.
The Urpower 2nd Gen 300ml Aroma Essential Oil Diffuser produces a stronger stream of mist than most diffusers we tested. Compared to other models we looked at, its tank size is larger, its price is lower, its footprint is smaller, and it has a clean and simple design. Other handy features aren’t unique or essential but set the Urpower apart anyway—there’s a 3-option shutoff timer, lights that can cycle through seven colors, and 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 mL tank is three times the size of those in most other diffusers at the same price, allowing this model to continually produce mist for seven hours—over twice as long as many competitors with smaller tanks. 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, a common but not universal feature.
The stream of mist from our favorite diffuser is tied for the strongest we’ve seen from any unit, both in volume and in plume height. Most units produce mist at a fraction of the rate that this one does. That stream translates to a scent that’s more noticeable than much of the competition. It’s also just pleasant to look at.
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, taking up half the footprint of many other models (including some with smaller tanks). It doesn’t draw attention to itself, and it’s easy to wipe out with a damp cloth between uses, especially compared to units with a second, decorative lid.
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 may make it a little harder for kids to open the diffuser and mess with the water, but it also means it’s harder for adults.
Our favorite diffuser is also one of the most affordable. You’ll be hard pressed to find any diffuser that’s more than a few bucks less expensive, and you could easily spend three or even five times the price on a unit that’s not as effective. Like most ultrasonic diffusers, this one is quiet, though you can hear a small whirring sound if you put your ear really close.
Senior staff writer Jackie Reeve reports that after over 3 years, her Urpower diffuser still works perfectly and “the color-changing lights are a fun extra on my desk.” Even though it needs regular cleaning, she says it’s “pretty unfussy, even when I haven’t used it in a while and it needs extra attention.”
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 it wasn’t an issue after I knew the trick.
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, the noise 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.
While this diffuser has a neutral design compared to much of the competition, it is noticeably made of plastic. You can find diffusers made of much more attractive materials.
With as strong a stream of mist as our pick, this diffuser has a larger tank you won’t have to refill as often. However, it takes up more space, and the faux-wood look isn’t for everyone.
This 500 mL model is nearly identical to the Asakuki.
The Asakuki 500ml Essential Oil Diffuser produces an equally strong stream of mist compared to our pick, but with a larger tank, it lasts even longer—up to 16 hours on its weakest setting, and around 10 hours on the higher settings. It lights up in seven colors and has LED lights that are a bit more subtle than our top pick, and it’s just as quiet. However, it takes up more space than our top pick, and the faux-wood base looks, well, pretty faux. We tested this side by side against the Urpower 500ml Aromatherapy Essential Oil Diffuser, confirmed the two are nearly identical, and we recommend whichever you prefer (either based on price or aesthetics). At the time of writing, both models are available in similar faux wood options.
A 500 mL tank is five times the size of most other diffusers at the same price, and nearly double the size of our top pick. Both the Asakuki and Urpower diffusers have three timer options to run for one, two, or three hours. Unlike all the other diffusers we tested, these models have an option to produce a weaker stream of mist for up to 16 hours, making these the only diffusers we recommend that can run continuously all day.
The Asakuki includes seven options for light colors with two brightnesses each, or you can run the unit with no light at all. The indicator light is weaker than that of our top pick, a plus if you’ll be running the diffuser while you sleep. The same goes for the Urpower.
The design of this diffuser isn’t our favorite: it’s larger and flatter than our pick, taking up more space and standing out a little more (and not in a good way). The plastic is a bit shinier, too. The faux-wood base is potentially an eyesore, and might not suit everyone’s tastes. We think either could work at anyone’s home as long as they’re okay with the bigger footprint—and with a larger tank and longer runtime, a 500 mL diffuser could be particularly well-suited to a business (like, say, a yoga studio) where it could run all day on a low setting.
The lid on these diffusers doesn’t snap onto the base, making it a good choice if you have trouble gripping or twisting. However, it’s less secure than our pick’s lid, which is a concern if you have curious children who want to get a look inside.
One of our senior staff engineers has been using a Asakuki diffuser for several years and reports that it’s still working perfectly, even with consistent, regular use.
This compact model is the most attractive diffuser we recommend, but its smaller tank doesn’t last as long and its stream of mist isn’t as powerful as our pick’s. It’s also far pricier.
If you want a diffuser that’s very good looking, we like the Vitruvi Stone Diffuser. The stream of mist is stronger than that of most other small, stylish diffusers, though not as strong as our top pick’s, and the Vitruvi only runs continuously for three hours on a single fill. It has a porcelain shell and comes in several understated colors, including black, white, blush, sage, and terracotta. A small ring around the bottom can light up, for some subtle mood-setting. The LED indicator lights are small and placed on the back of the unit, making this the best choice if you’d like to run the diffuser in a dark space.
At 100 mL, the tank is one-third the size of our top pick’s, and you’ll have to refill it more often if you’d like it to run continuously for more than a few hours. This diffuser has an option for intermittent diffusing, which our pick lacks; on this setting it can run for seven hours. I personally don’t like this setting as much, as the continuous stream of mist makes for a nicer ambience.
There’s only one light option on the Vitruvi: a small ring of yellow around the bottom. It’s more elegant than the multi-colored light options on our picks (though perhaps not as fun).
The conical design and stone-like texture of the porcelain shell make this diffuser the most pleasing to look at even when it’s not running. Our pick is an appliance; the Vitruvi is more of a small sculpture.
The two lids, one plastic and one stone, are annoying to remove to refill the unit or clean it out. Otherwise, the diffuser is easy to wipe out between uses.
Between the smaller size, the elegant appearance, and the annoyance of the two lids, we think this diffuser could be a good fit if you don’t expect to use it on a daily basis and would prefer something attractive that you could display on a shelf or mantel as a functional complement to your decor.
If your top priority is a strong smell, go with a nebulizer. It’s pricier than our top pick and harder than ultrasonic models to clean, but unbeatable at filling a room (or a few) with scent.
If you want a stronger aroma and are willing to accept a more difficult cleaning process, we like the Organic Aromas Raindrop 2.0 Nebulizing Essential Oil Diffuser. Of the five nebulizers we tested (which were all great at diffusing), the Raindrop 2.0 is 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—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 to be 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—and a more difficult overall cleaning process than ultrasonic picks—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.
In late fall 2020, we looked at how essential-oil diffusers (and a nebulizer) affect indoor air quality. We tested multiple high-quality pure essential oils and blends from Doterra, Plant Therapy, and Young Living, using the Urpower 300ml, Asakuki 500ml, Vitruvi Stone, and Urpower 2nd Gen 100ml diffusers and the Organic Aromas Raindrop 2.0 nebulizer. The test space was Wirecutter senior staff writer Tim Heffernan’s roughly 200-square-foot bedroom, and he measured how the machines affected the number of airborne particles using the same Aerotrak 9306 particle counter that he uses for our guide to air purifiers. He closed the windows and shut off his apartment’s ventilation system during the tests, and filled the diffusers with distilled water, to ensure that no dissolved minerals made it into the air and affected the results. The oils were added in the quantities recommended by the manufacturers.
As expected, all the machines raised the number of fine particles in the air—after all, they work by doing exactly that. The numbers here show the increase in particles of 0.3-micron diameter (0.3 micron being the HEPA test standard):
For each test, Tim ran the particle counter for five minutes with the diffuser or nebulizer off, to get a baseline reading of the air quality in the room, and then ran them for 30 minutes on their highest or continuous settings. He placed the diffusers and the nebulizer on his bedside table (a typical location for these things), with the particle counter a few feet away on the headboard. After 15 minutes, he moved the particle counter to a second table on the far side of the bed, about 8 feet away, to see if distance affected the airborne particle count.
There are two main takeaways from our findings. First, the nebulizer showed a much greater increase in particulate levels in the air than the diffusers. That’s not surprising: Nebulizers create a fine mist of pure essential-oil droplets, while diffusers create a mist composed mostly of water, with a small amount of essential oil mixed in. (Most diffuser makers recommend about 4 or 5 drops of essential oil per 100 milliliters of water.) The water rapidly evaporates and, as a result, does not show up in the particle counts; what’s left over are the relatively sparse oil droplets.
Second, the diffusers created a fairly uniform concentration of airborne particles throughout the room, while the nebulizer concentrated them in its immediate vicinity—note the dropoff at minute 20, when Tim moved the particle counter to the far side of the bed.
The question is: Does any of this matter? It’s well-established that fine particles of soot, smoke, and dust have negative health impacts when inhaled, but what about fine droplets of essential oils?
Tim spoke with Sachiko Koyama, an olfactory biologist at Indiana University and co-author of a comprehensive review of the ways essential oils’ impacts on the body are affected by the mode of delivery (by inhalation, topically, or by ingestion). In general, she said, aromatherapeutic uses of essential oils can be considered safe, because the oils themselves are not inherently dangerous when inhaled and because their concentration in the air is low. Koyama also noted that much higher concentrations are used in the established practice of smell training, which may help to restore a sense of smell to people who have lost it (including some COVID-19 survivors). Koyama did note that some people are allergic to components found in essential oils, and that overexposure to essential oils may create sensitivity to them in people who previously were not negatively affected. As noted above, in “Who should get this,” there are also anecdotal reports of essential oils negatively affecting the breathing of asthmatics and non-asthmatics alike. Ingesting essential oils can be injurious and even fatal, so keep them out of the reach of children. And as Wirecutter’s Kaitlyn Wells reports, some airborne essential oils can be dangerous to pets. But all that noted, “if you don’t have a specifical allergy,” Koyama said, “for most people I don’t think it will cause a problem.”
In 2021, we tested the Canopy Diffuser. It’s different from all our picks in that, rather than being ultrasonic or a nebulizer, it evaporates oils directly. You soak oils into a little puck of diatomite, a finely porous natural mineral made of the shells of tiny sea creatures; a fan blows air past the puck, evaporating the oil. It’s a neat system in theory because it requires no cleaning beyond an occasional wipe-down. But in practice, we found the production of aroma very weak. We also don’t like that this model comes with only one puck—you need to purchase separate ones if you want to switch scents regularly. And the “diffusion well,” a larger diatomite puck that sits inside the machine and delivers up to three weeks’ worth of continuous aroma, can work only with 5 mL bottles, as the common ⅓-ounce (10 mL) bottles are too tall and prevent the cover from reattaching to the machine.
The Kumi Stone Diffuser was demoted from an also-great pick due to supply issues in late 2022. If you happen to find one, it’s a great device and a clone of the Vitruvi Stone Diffuser—they’re such dead ringers in appearance, functions, and materials that it’s clear they come off the same assembly line—or at least their component parts do. (This isn’t speculation: The common origin of diffuser components is something that a source confirmed.) The main difference between the Kumi Stone Diffuser and the Vitruvi Stone Diffuser is price, as the Kumi typically costs less than half as much. Our testing revealed that the same drawbacks we identified in the Vitruvi apply to the Kumi, as well: At 100 mL, it doesn’t have a large capacity, doesn’t add scent to a space larger than a bedroom, and runs dry within eight hours. In addition, it comes only in white, whereas the Vitruvi diffuser is available in various earthy colors. The Kumi diffuser has three output settings (high, low, and intermittent) and three light settings (bright white, low, and off for sleeping).
We used to recommend the Vivitest Ceramic diffuser as a dupe for the Vitruvi Stone; they look nearly identical, and are made from the same materials, but the Vivitest costs a fraction of what the Virtuvi does. However, in early 2023 we saw that both satisfaction with the product and the seller had significantly dropped for the Vivitest. In particular, many buyers complained that the Vivitest simply stopped working for them after about a year of use. Though we didn’t have any issues while testing it ourselves, we have removed our recommendation until we can inspect it further.
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 larger version of the Mia. It has an option to run in intervals, 10 minutes on and 20 minutes off, for 24 hours. While the mist stream is stronger than the Mia’s, it’s still weaker than that of our picks. Also, one Amazon reviewer notes that the LEDs are strong: “Wow the lights are like a lighthouse beacon in the night.”
There is a 100 mL version of the Urpower Essential Oil Diffuser, another popular model from a manufacturer that leads the space. At that size, you have a lot more design options, and we felt we could recommend something more attractive than this model’s plastic finish—that led us to the Vitruvi, our also-great pick, as well as several other stylish small diffusers we considered and dismissed.
We like that the Now Solutions Real Bamboo Ultrasonic Oil Diffuser is made of real wood. Plus, at the time of testing, Fakespot gave the Amazon reviews a B and since then it has risen to an A, 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. However, the stream of mist is weaker than our top picks, and it doesn’t look as elegant as the fancy diffuser we like.
Though they are slightly different shapes, the InnoGear Aromatherapy Essential Oil Diffuser is functionally identical to our former runner-up pick, the 120 mL Urpower. 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.
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.
In previous years we tested the Diffuser World Aroma-Express and the Diffuser World Aroma-Infinity, both of them nebulizers. The Aroma-Express has no option to diffuse oil intermittently, which we found to be an important feature for nebulizers. It also made a grinding noise as it ran. The Aroma-Infinity does have an option to diffuse oils intermittently, but it’s not worth the price for most people. As of late 2022, they seem to be out of stock in most places.
In past versions of this guide we also tested: The InnoGear 500ml Aromatherapy Essential Oil Diffuser and the Welledia Pleasant Essential Oil Glass Nebulizing Diffuser, both of which are now discontinued.
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 cleaning it immediately after running it with a thick oil like sandalwood). If you’re switching oils, clean it 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, possibly due to the diffusers’ much smaller output than humidifiers.
This article was edited by Daniela Gorny and Christine Ryan.
Amanda Z. Naprawa, Essential Oils: What You Should Know, Berkeley Wellness, March 1, 2016
How to Clean Your Essential Oil Diffuser, Essential Oil Haven
Weekly Five, Essential oil diffuser review, YouTube, August 4, 2015
Diana Balekian MD, Aidan Long MD, Dennis K. Ledford, MD, FAAAAI, Essential Oil Diffusers and Asthma, American Academy of Allergy Asthma & Immunology, December 1, 2015
Sachiko Koyama, telephone interview, December 10, 2020
Shannon Palus is a former Wirecutter senior staff writer. She tested countless health and wellness products from 2016 to 2018.
Essential oils can be toxic to pets. Don’t apply any directly to an animal’s skin, and avoid using an active diffuser in the same room as your pets.
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