LEVOIT OasisMist 4.5L Review: a smart warm & cool mist humidifier that’s good, but a bit overhyped

I’ve been using the LEVOIT OasisMist 4.5L in a bedroom and a small living room for a while now, mainly because dry air was wrecking my sinuses in winter. On paper, it ticks a lot of boxes: warm and cool mist, app control, auto humidity, top-fill, essential oils, quiet, and meant for up to around 430 ft². Basically, it looks like the "do-it-all" humidifier that should cover most people’s needs.

In reality, it does the core job: it puts moisture in the air and helps with dry nose, scratchy throat, and that static shock feeling you get in very dry rooms. I noticed a difference in a couple of nights for sleep and less morning congestion. But once you get past that, you start seeing all the little design choices that are either handy or slightly annoying depending on how picky you are.

I’m not someone who babies appliances, but I do care about cleaning and noise because this thing sits right by the bed. Compared to cheaper basic humidifiers I’ve used, this one feels more modern because of the app and auto mode, but it’s not perfect. Some things are really well thought out like the top-fill, and some are just clumsy like certain parts being a pain to clean or the lid design.

If you’re expecting a magic solution that runs itself and never needs effort, this isn’t it. If you’re okay with a bit of maintenance and you actually like tweaking stuff via an app, it’s pretty solid. The key question is whether the extra price over a simpler unit is worth it for you, and for me, that answer is kind of in the middle: good product, but not the best deal for everyone.

The big question: is this worth the roughly $110–$120 price tag (depending on sales and tax)? For that amount, you’re paying for a mix of smart features, warm + cool mist, and a decent-sized tank. If you’re actually going to use the app, Auto Mode, scheduling, and you care about dual nozzles and quiet operation, then the value is decent. It does what it says, and the app is genuinely one of the better parts of the experience.

However, when you compare it to other brands, it’s not a slam dunk. Some users directly compared it with cheaper smart humidifiers around $80 that offer similar features: app control, top-fill, warm/cool mist. In those comparisons, LEVOIT often loses on small usability details like easier-to-remove nozzles, better tank orientation, or extra touches like an ambient light (which this one doesn’t have at all). For a product that ends up over $100 with tax, the rough edges in cleaning and design stand out more.

Also, factor in the hidden cost: if your tap water is hard, you’ll basically need to use distilled or RO water to avoid white dust and heavy scaling. That’s not unique to this model, but it does mean ongoing cost or effort. LEVOIT didn’t include a serious mineral filter system here, which would have helped justify the price and also brought them recurring filter sales. Instead, you get a basic sponge filter that doesn’t do much for calcification.

So in terms of value, I’d rate it as "good but not outstanding." If you catch it on sale and you like the LEVOIT ecosystem and VeSync app, it’s a solid buy. If you’re more price-sensitive and don’t care much about app control, you can probably find simpler humidifiers that humidify just as well for less, and maybe even clean up easier. The product is decent; the price is just a bit on the high side for what you actually get in real-world use.

From a distance, the design is pretty standard: a white rectangular body, around 10.8" deep, 6" wide, and almost 12" tall. It doesn’t scream for attention and blends into most bedrooms. I like that the front panel has clearly labeled buttons, not just random icons. For anyone who isn’t techy, that’s a plus. The display is bright enough to see during the day, and you can turn it off via the app at night if the light bothers you.

The top-fill design is one of the best parts. You just lift the lid and pour water in. No juggling a slippery tank over the sink. But the lid itself is where the design gets a bit dumb. There’s a little cutout area where you slide your fingers to lift it. More than once, the lid slipped and fell right into the tank water. It’s not the end of the world, but it feels like something that should have been caught in testing. A more secure grip or a different handle shape would fix this easily.

The tank orientation is another minor but real annoyance. The shape isn’t totally symmetrical, so when you take the tank section off for cleaning or moving, you need to get used to which way it sits back onto the base. The first days, I kept turning it around trying to line it up correctly. After a while you get used to it, but compared to some competitors where the tank just drops in any way, this feels less intuitive.

On top, the dual 360° nozzles are a good idea. You can point mist toward the bed and away from walls or electronics. The downside is that the nozzle assembly isn’t super friendly to disassemble, so when it’s time to really clean inside that part, you’ll probably end up using small tools or pliers to pull things apart carefully. Overall, the design is decent but not polished. It looks fine, the concept is good, but a few details make it feel more fiddly than it needs to be.

From a comfort point of view, the first thing that stood out is how quiet it is. LEVOIT claims around 26 dB, and honestly, it feels about that. On low or Auto, I can sleep with it next to the bed without it bothering me. There’s no constant dripping sound or harsh fan noise, which is something that annoyed me with cheaper units I’ve used before. For a bedroom, this is a big plus.

In terms of air comfort, after a few nights I definitely had less dry nose and less waking up with a scratchy throat. I also noticed less static in blankets and clothes. When I used the warm mist setting while congested, it felt a bit more soothing than cool mist, especially in winter. It’s not life-changing, but it’s enough to make breathing feel easier, especially if your place is heated with dry forced air or you live in a low-humidity area.

The smart control side is a mixed bag for comfort. On one hand, being able to grab my phone, check humidity, and tweak mist levels from bed is genuinely practical. I used the app more than the physical buttons. Scheduling is handy too: you can set it to turn on before bedtime and off in the morning. On the other hand, some things are oddly inconvenient. For example, there’s no physical button on the unit to kill the display light; you have to go into the app to turn it off. If you misplace your phone or the app glitches, that’s just annoying.

Sleep Mode sounds good on paper, but in practice it’s kind of useless. It runs at a low mist output but doesn’t intelligently stop at a humidity ceiling unless you’ve set a target. So if your room is small and closed, the humidity can climb higher than you actually want. Overall, comfort is good: quiet, effective enough, and the app is genuinely useful. But some design decisions around controls and modes make it less smooth than it could be.

The whole unit is basically plastic, which is expected at this price, and it feels decent but not premium. Nothing feels super flimsy, but it also doesn’t give that tank-like impression. The weight (around 5.3 lbs empty) makes it easy to move around, even when the tank isn’t full. For something that mostly just sits on a table or nightstand, the materials are fine, but don’t expect anything fancy.

The main issue for me is less about the plastic itself and more about the internal design for cleaning. Ultrasonic humidifiers always need regular cleaning to avoid mold, bacteria, and mineral buildup. With this one, some areas are easy to reach thanks to the wide top opening. Basic rinsing of the tank and wiping the inside isn’t too bad. LEVOIT even includes a small cleaning brush and a sponge filter. But then there are those small corners and the nozzle area that are a pain.

The nozzle assembly on top doesn’t just pop off easily. If you want to deep-clean inside that part, you basically have to be careful and sometimes use tools like pliers to separate pieces. It’s doable, but it’s not friendly. Compared to some other brands where the nozzle comes off in one simple piece, this is overcomplicated. Also, there are several little crevices where mold and gunk can start forming if you’re not on top of your cleaning routine.

Because there’s no serious demineralization filter, if you use hard tap water, you’ll likely get white dust around the room and more calcification inside the unit. Even with frequent cleaning and additives, some users still reported buildup in tricky spots. Distilled or RO water is almost mandatory if you want to keep it clean with less effort. So, materials are okay for what it is, but the internal layout makes maintenance more annoying than it needs to be, especially for people who don’t want to spend time scrubbing small parts every week.

Performance-wise, it does what a humidifier should do: it raises humidity and keeps it more stable than running a cheap non-smart unit. In a typical bedroom around 150–200 ft² in a dry climate, I could get from very dry (around 25–30% RH) up to the low-to-mid 40s in a reasonable amount of time, especially if I closed the door. For sinuses and dry throat at night, that was enough to feel a clear difference in a couple of nights.

The warm and cool mist modes both work, but the difference you feel in the room is more about how fast the humidity rises than the actual air temperature. Warm mist helps slightly with quicker humidification and feels nicer when you’re sick, but don’t expect it to heat the room. LEVOIT limits the warm mist temp between about 40–60°C for safety, so it’s not boiling steam like old-school vaporizers. Mist output on high is strong, and the dual nozzles help spread it. For very dry desert conditions, though, some users (and I’d agree) find it struggles to push much past 40% in a 200 ft² room unless you really let it run hard and keep the space closed.

The Auto Mode is handy but not perfect. It aims for 40–60% RH, and you can tweak your target in the app. The built-in humidity sensor is fairly accurate, but like any humidifier, if it’s reading right next to the unit, it can think the room is more humid than it really is. Using a separate hygrometer on the other side of the room is a good idea. Sleep Mode, honestly, isn’t great. It just runs at low output and can end up overshooting humidity because it doesn’t stop at a specific level by itself unless you’ve set a target in the app.

Noise-wise, it’s very quiet. On low and in Auto, I barely noticed it, more like a soft hum. It’s fine for light sleepers. No loud gurgling or weird mechanical noises. Overall, performance is solid for small to medium rooms in normal dry conditions, but if you live in really dry desert air and want 45–50% humidity in a bigger room, you might find it underpowered and running near constantly.

On a basic level, this is a 4.5L ultrasonic humidifier with both warm and cool mist, meant for bedrooms or medium rooms up to roughly 430 ft². It runs off 120V, uses about 12W, and weighs around 5.3 lbs. It’s a top-fill model, which means you pour water directly in from the top instead of dragging a tank to the sink and flipping it upside down. You get dual 360° nozzles, so you can point the mist in two directions, plus an aroma pad if you’re into essential oils.

The big selling point is the "smart" side. It connects to LEVOIT’s VeSync app, where you can: see the room humidity, adjust mist level, switch between warm/cool mist, set schedules, and use Auto Mode. Auto Mode tries to keep humidity between about 40–60% RH, or you can set a specific target in the app. There’s also a basic control panel on the front with labeled buttons, so you don’t have to guess what each icon does, which I actually appreciate.

Daily use is simple: fill water from the top, set your mode (I mostly used Auto or level 2 mist), and let it run. The tank size is decent. At moderate output, a full tank can easily last overnight and then some. At max power, especially with warm mist, it drains faster but that’s expected. The unit will shut off when empty, so you don’t have to worry about it burning out.

So in practice, the "presentation" is: a fairly compact, app-connected humidifier that tries to replace both a basic bedroom humidifier and a small warm-mist unit. It does cover a lot of features, but you should keep in mind it’s still an ultrasonic humidifier without a real demineralization filter, so water quality matters a lot if you don’t want white dust and buildup everywhere.

I mainly got this to help with dry sinuses, congestion, and rough sleep in winter, and on that front it does a good job. After a couple of nights running it in the bedroom, I woke up with less nosebleed risk and less of that tight, dry feeling in my throat. When I had a mild cold, running it on warm mist at night made breathing a bit easier and reduced that dry cough you get in heated air.

For people in very dry climates, it’s effective but with limits. In a bedroom around 150–200 ft², I could get humidity from the low 20s to the low-to-mid 40s, which is already a big comfort gain. But pushing it reliably to 50% in a desert-like environment is tough. One user who works in indoor air quality even said it couldn’t get their 200 ft² desert room above 40% despite frequent water changes and cleaning. So, it clearly helps, but it’s not a powerhouse for extreme dryness.

The Auto Mode is supposed to make things easier by holding a range like 40–60%, and when it works, it’s nice because you just set it and forget it. But the internal sensor reading near the unit can be slightly higher than the rest of the room, so the humidifier may slow down thinking it’s done while the far side of the room is still drier. Using a separate hygrometer across the room is honestly the way to know what’s really going on. The app lets you fine-tune things, which helps, but it’s not totally plug-and-play perfect.

Overall, in terms of symptom relief and day-to-day comfort, I’d call it pretty solid. It’s not some miracle machine, but if your air is dry and you’re dealing with sinus irritation or dry skin, it definitely improves the situation. Just keep your expectations realistic about how high it can push humidity in tough conditions and remember that you still have to keep it clean for it to stay effective over time.