The best humidifiers you can buy: Expert tested

ZDNET's top humidifier pick is the Levoit Classic 300S humidifier for its smart capabilities, practical design, water capacity, and ease of use. See how our other picks stack up with each other and compare key categories like price and added features. 

*1 Gallon = 3.78 Liters

*Lowest non-discounted price at the time of writing. Please note that prices may vary based on retailer and available promotions, sales, or discounts.

With tons of humidifier options on the market, it isn't easy to sort the best ones. The perfect fit for you is a humidifier that fits your physical space and your wants and needs for a product. 

Here's a few things to keep in mind as you embark on your best humidifier search. 

• Water Tank Capacity: The capacity of a humidifier's water tank ultimately decides how long the device can run without refills, what space its fit for, and how portable a humidifier is. The best humidifiers offer water tanks large enough for everyday ease without hassle, but not so enormous that its use becomes impractical or unsanitary. 

• Smart Capabilities: Like most tech today, humidifiers have entered the modern era. Certain humidifiers offer "smart" features like app control, which allows you to change mist settings, turn your device on and off, and sometimes even create schedules. The best humidifiers offer top of the line settings for a customized, yet functional experience, and it's key to figure out what functions you do or don't want your humidifier to have so you can search accordingly. 

• Price: Humidifiers can range from around $30 upwards to a few hundred dollars depending on brand, size, design, and water capacity. We aimed to keep our top picks all under $100, with most priced even under $75, to ensure a quality pick at a practical price. It's good to keep in mind that humidifiers sometimes see discounts across retailers, too, so keep your eyes peeled when searching. Ultimately, decide on a budget that fits your lifestyle to help narrow down your search. 

ZDNET has expert researched and gone hands-one with several picks on this list. We've spent time testing these products during our daily activities and lives to rate their function, style, features, and more -- not just for a day or two, but over the course of a few weeks to really get a feel for a product's add-in value to your life. 

If we think another product is worth your money, we'll update this list or write up a spotlight review highlighting its best qualities and specifying who it's for. 

Plus, we are routinely scouring the web for new products that are worthy of testing, and following news on product rollouts and upgrades, and sourcing the best deals. We know buying anything in the current economy is not just for your whims, and that's why this list, as well as our other advice, is tailored to your needs, wants, and your budget -- and why our picks are expert-tested and expert-vetted. 

The ideal humidity in a home is to some level dependent upon personal preference, though the Centers for Disease Control and Prevention (CDC) recommends keeping the humidity levels in your home "as low as you can" and "no higher than 50% all day long." 

Most professionals online suggest keeping your home's humidity somewhere between 30-50%, though some outlets say up to 60% is fine. Just keep in mind that an increase in water vapor in your home increases the chances of mold and mildew growth, and that humidity rates fluctuate throughout the day and throughout the seasons. The CDC additionally suggests maintaining proper ventilation within your home, especially in areas such as kitchens or bathrooms. 

The ideal water tank capacity or tank size for the humidifier that best fits your needs is going to depend on the size of the room you are looking to house your humidifier in and how often you plan on running your device. If you're only wanting to up your room humidity when you sleep, you won't need as large of a water tank as you would if you're planning to run your humidifier all day. 

It's key to keep in mind your portability needs, too. Do you need to move this humidifier around a lot? Will it remain in one room and one spot? If you want a humidifier with better portability, a smaller tank size may be best so you aren't lugging a larger device with a copious amount of water back and forth. 

Generally, you can choose your humidifier based on three different room sizes: small, medium, and large. Here's a ballpark room size to water tank capacity to use as a basic guideline. 

• Small room: A small room may have a square footage of fewer than 400 feet. A humidifier with about or under 1.5 gallons would work well. 
• Medium room: A medium room may have square footage between 400 and 1,000 feet. A humidifier with 1-3 gallons is ideal. 
• Large room: A large room may have a square footage of more than 1,000 feet. A humidifier with more than three gallons is likely needed. 

As you're looking for your humidifier, you'll see that most brands give an idea of the room size the device is appropriate for, or the number of gallons the water tank holds. 

Portable tabletop or room humidifiers are not your only option to add moisture into your home and maintain a consistent humidity. If you live in a climate that is dry all year round, or are particularly sensitive to low humidity and prone to dryness, you may want to consider a whole home humidifier. 

Whole house humidifiers can be installed either inside your home's HVAC system, or mounted on the outside. They are traditionally connected to a house's electricity and plumbing though specific installation methods can vary in complexity and differ by humidifier types, brands and models. While a whole house humidifier may be the best option, keep in mind that some drawbacks include installation requirements, maintenance and upkeep expenses on a much larger scale, and the potential for mold and mildew growth. 

Humidifiers are often used to soothe and relieve common effects of dry indoor air: soar throats, nosebleeds, chapped lips, dry and itchy skin, closed nasal passages, and more -- and they're great for maintaining a consistent humidity throughout your home. Primarily during colder weather, an increase in heat use and the changes in the weather can generate less moisture in home environments, leading to uncomfortable conditions. 

Humidity acts as a moisturizing agent that soothes seasonal affiliated dryness in children and adults, but it can also be used to provide extra water vapor to plants, babies, and more for similar reasons year-round. Humidifiers require regular upkeep and maintenance to remain healthy and clean for users. 

Ideally, yes. Like many other home appliances that incorporate water (hello, coffee makers), distilled water is typically recommended to be utilized in your humidifier's system. 

This doesn't mean that you can't use bottled water or tap water (especially if your tap water is drinkable), but keep in mind that it may contain more unsanitary particles or minerals and build-up that will percolate through your humidifier, potentially resulting in more frequent cleaning and even less product longevity over time. Some humidifiers are equipped with a water filter to help prevent this, but generally, you're probably just better off to utilize distilled water if you can. 

All in all, distilled, demineralized, and purified water will typically be less likely to result in harmful bacteria growth (i.e. mold) inside of your humidifier, but it's not always necessary. Ultimately, fill at your own risk. 

Essential oils should only be added to your humidifier if your device's manual specifically states that it is designed to do so. Many humidifier options on the market do offer a designated spot to incorporate essential oils, so be sure to select a model that does if that's one of your desires. 

Otherwise, do not put essential oils in the water reservoir or any other place within your humidifier. It will cause damage to your device's system. 

Humidifiers require constant maintenance to ensure they are safely working, and avoid mold buildup, mineral buildup and  stale water. Most humidifiers will come with instructions on how often and how-to clean your device. It is usually best to follow the manufacturer instructions, but ultimately how often you clean your humidifier comes down to preference. 

More: How to clean a humidifier

For example, my Levoit 200S recommends a full clean once a week, but I use distilled water and make sure to wipe out the tank and top nozzle with each fill, so I admittedly only clean it about once every two weeks. 

Evaporative humidifiers build upon the simple concept of naturally letting moisture evaporate into the environment to relieve dryness. These types of humidifiers speed up this process by using a fan that blows air through a moistened wick filter. In turn, as the water evaporates, it is expelled from the humidifier as water vapor. 

On the other hand, ultrasonic humidifiers use two ceramic plates that vibrate at a high frequency to create humidity. The plate vibrations produce a fine mist that spreads into the air, where it evaporates, thus producing humidity. Ultrasonic humidifiers require purified or distilled water and can be more upkeep. 

Both types of humidifiers can generate water vapor in your space, but you may find that one option is better for you than the other, depending on your wants and needs. 

The main difference between cool mist and warm mist humidifiers is that the latter emit hot steam. Both humidifier variations add moisture to your air, and there's a few pros and cons of each to consider. 

Warm mist humidifiers can add some warmth to the air during colder seasons, are better at reducing bacteria and germs, and are often quieter and less expensive than cool mist humidifiers. However, hot steam can be a hazard to children and pets, and warm mist can potentially cause nasal passages to swell which isn't great if you're combatting a cold. 

On the flip side, cool mist humidifiers are solid picks for year-round operation, particularly in arid climates that see little rain. Cool mist humidifiers are also safer around pets and kids, and are great to use when you're experiencing a cold or congestion. The downside to cool mist options is that without heat, they accumulate bacteria growth easier and can be slightly louder than warm mist designs. 

Ultimately, the choice between cool mist or warm mist is up to you, and both humidifier options are effective at adding moisture to the air in your home and maintaining a consistent humidity level. 

While ZDNET rounded up the best humidifiers according to research and personal experience from our experts, there are tons of other options available across retailers that may fit your needs. Here's a few other humidifier options to consider for adding the perfect amount of water vapor to your space.