A cool-mist humidifier can help maintain skin moisture and prevent dryness — plus, the top-rated models from our tests are especially quiet and efficient
Cool-mist humidifiers have many benefits and are considered safer than warm-mist models because they don’t involve hot water.
By Tobie Stanger
Cool-mist humidifiers are the choice of most Americans seeking to alleviate dryness in their homes. These machines dominate the market because they pose fewer safety risks than warm-mist humidifiers, also known as vaporizers.
Unlike warm-mist humidifiers, cool-mist versions add moisture to indoor air without boiling water and producing steam. With no potential to burn or scald, cool-mist humidifiers are the only humidifier type that pediatricians recommend for households with babies and young children.
“They’re also the best choice for homes with pets prone to investigating mysterious appliances,” says Misha Kollontai, who leads humidifier testing at Consumer Reports.
Read below for more on the advantages of cool-mist humidifiers, and see the best cool-mist models in each of the humidifier sizes Consumer Reports tests. For test results and more options, CR members can check our complete humidifier ratings, which include units that range from personal size all the way up to consoles that can humidify 1,000 square feet or more.
Benefits of a Cool-Mist Humidifier
Even in homes without curious critters or toddling tots, cool-mist humidifiers have benefits. Here’s how they excel over other types.
Energy efficiency: Cool-mist models use significantly less energy than warm-mist models. The reason is that they work without boiling water, which requires a fair amount of electricity, Kollontai says. Depending on the unit’s style, a cool-mist humidifier uses one of two mechanisms to add moisture to the air.
Evaporative cool-mist humidifiers use a fan to blow air through a wet wick; the air cools as it picks up moisture from the wick. Periodically, you’ll need to replace a filter or wick, which can run from $10 to $20.
Ultrasonic cool-mist models—the majority of units in CR’s ratings—use small vibrating diaphragms called nebulizers to create a mist. Ultrasonic units typically are less noisy than evaporative models because they have no fan. But their mist can leave a white dust—tiny particles of mineral precipitate—on surfaces. (To prevent that dust, you can use distilled or filtered water instead of tap water.)
Help for stuffy noses: Cool mist can help shrink swelling in nasal passages, making breathing easier, according to the Food and Drug Administration. By contrast, warm mist can cause nasal passages to swell, making breathing more difficult, another reason the FDA doesn’t recommend their use for infants with coughs and colds.
Convenience in small sizes: In our ratings of small humidifiers, cool-mist models were judged more convenient as a whole vs. small warm-mist units—better known as vaporizers—reflecting factors such as ease of operation. Several small cool-mist units in our ratings have humidistats, which turn off the unit when the air reaches a set humidity level; none of the small vaporizers in our ratings have that feature. Small vaporizers typically don’t even have a power switch; they start working when you plug them into an outlet. (They do, however, shut off automatically when the tank is empty.)
More shopping choices: Cool-mist models make up more of the portable humidifier market than other types, says Marion Wilson-Spencer, a market analyst who covers humidifiers for Consumer Reports. In CR’s ratings, you can find cool-mist humidifiers in every size we test, including travel models, units for small, medium, and large rooms, and consoles for very large rooms of 1,000 square feet or more. In our ratings, you won’t find warm-mist units in travel or console sizes; you also won’t find dual-mist units in small, medium, or travel sizes.
Where a Cool-Mist Model Has No Advantage
One area where cool-mist humidifiers have no edge is in how well they do their basic job: adding moisture to the air. “Cool- and warm-mist units are equally effective at humidifying,” Kollontai says.
There’s also no way to generalize about which type is easier to clean. “It depends largely on the design,” Kollontai says. With either type, though, it’s crucial to clean the components regularly to prevent the growth of mold spores and other nasties that can lead to illness. Check the manufacturer’s directions for cleaning, as well as Consumer Reports’ advice on this key task.
When to Opt for a Warm-Mist or Dual-Mist Humidifier
The main reason for using a warm-mist humidifier is noise. Warm-mist models tend to be quieter because they don’t need a fan, nebulizer, or vibrating diaphragm to move moisture into the air. “The steam naturally escapes the tank,” Kollontai says.
For the best of both worlds, consider buying a dual-mist version, which lets you choose between cool and warm mist. There are 12 dual-mist units in CR’s ratings; two of these, sized for rooms between 300 and 499 square feet, have excellent Overall Scores. Six others, sized for larger rooms, have very good Overall Scores. “A dual-mist model allows you to take advantage of the soothing warm mist only when you truly think you need it, and to take advantage of the energy savings of cool otherwise,” Kollontai says.
Just steer clear of dual-mist units if you have kids or pets, because an inadvertent turn of the dial or press of a button can activate potentially scalding steam.
Best Cool-Mist Humidifiers From CR’s Tests
Choose the size that’s closest to the square footage of the space you want to humidify. These top-rated models earn solid scores for convenience, noise, and efficiency.
Travel/Personal (up to 25 sq. ft.)
Lasko UH150
The affordable cool-mist Lasko UH150 is the top among travel humidifiers. This little cutie—a compact model that’s just 3.7 inches square and 5.4 inches tall—aces every test we throw at it: output, convenience, noise, energy efficiency, operation using hard water, and humidistat accuracy. For its competitive price, you also get auto shutoff when the tank is empty, nightlight settings, and adjustable mist control. But you’ll need to regularly replace the absorbing filter or wick, and the 38-inch cord is relatively short.
Small Room (26 to 299 sq. ft.)
Babymoov Hygro (+)
The ultrasonic Babymoov Hygro (+), designed for rooms of around 215 square feet, is the highest-rated model in the small room category for a reason. It excels in almost every one of CR’s tests: output, noise, output with hard water, convenience, and energy efficiency. The Hygro (+) is the only small humidifier to earn a strong score for the accuracy of its humidistat, a device that measures relative humidity. Features include a nightlight that revolves through a rainbow of colors, automatic shutoff when the tank is empty, a timer, and the option to diffuse aromas. But its cord length, 58 inches, is on the short side.
Medium Room (300 to 499 sq. ft.)
Dreo HM524S
The Dreo HM524S is the top-rated midsized humidifier in our ratings, earning excellent scores in all of our six tests. The unit, designed for rooms of about 400 square feet, offers several attractive features that include an empty-tank indicator, automatic shutoff when the water runs out, and a fairly long cord (60 inches).
Large Room (500 to 999 sq. ft.)
Blueair InvisibleMist
The Blueair InvisibleMist can humidify a room of up to 500 square feet and is the highest-scoring large-room humidifier we test. It earns excellent marks in our convenience, efficiency, and hard water tests and earns near top-level marks for output and noise. It is also equipped with a few handy features, including an automatic shutoff when the tank is empty.
How CR Tests Humidifiers
In Consumer Reports’ humidifier lab, we evaluate models on six criteria: moisture output, convenience, noise, energy efficiency, humidistat accuracy, and output using hard water.
Our moisture output tests are conducted in a chamber set to 70° F and 30 percent relative humidity, an industry standard for testing humidifiers. Manufacturers typically claim that their humidifiers are intended for a specific room size or area, so we measure a humidifier’s moisture output and calculate how well it does in the specified area.
We also gauge how convenient a humidifier is to use. Our testers assess how easy it is to set up and operate, as well as how easy it is to clean, which is important because you may need to empty the tank daily and clean the humidifier regularly to prevent bacteria from developing. We measure the sound (in decibels) that a humidifier generates when it’s running at its highest speed. Some are louder than others, and if you use a humidifier in your bedroom, you’ll want to steer clear of noisy models that could disturb your sleep.
Testers calculate the amount of energy each model uses to emit a gallon of water into the air. Our humidistat accuracy test measures how well each humidifier reaches and maintains a set humidity level.
Finally, we test a humidifier’s moisture output when hard water is used. We conduct this test because the dissolved minerals in hard water can clog a humidifier, which decreases its moisture output.
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