I’m a Home Expert— These Are the Things to Know Before Buying a Humidifier

Waking up with a scratchy throat, dry skin, or a stuffy nose? Dry indoor air could be part of the problem, especially during the winter when cold outdoor air gets heated, lowering its relative humidity and making indoor spaces feel especially dry. A humidifier can help by adding that moisture back, making your bedroom or living space more comfortable while also protecting wood furniture and floors from excessive dryness.

At the Good Housekeeping Institute Home Improvement & Outdoor Lab, our experts test humidifiers year round, evaluating everything from moisture output and noise levels to how easy the machines are to fill and clean. In our latest review, we evaluated 25 models, so we know which features make a difference and which ones you can live without.

As with most home appliances, there's no one-size-fits-all solution. A small humidifier might be perfect for a bedroom but struggle to add enough moisture to a large living room. The type matters too, especially if you have young children, pets, or allergies. And since humidifiers require regular cleaning, choosing a model that's easy to maintain is just as important as its ability to add moisture to the air.

All humidifiers serve the same basic purpose: adding moisture to dry indoor air. But the way they accomplish that varies quite a bit. Portable models generally fall into three categories: ultrasonic, evaporative, and warm-mist. There are also whole-house humidifiers designed to add moisture across multiple rooms. Each option has its own advantages and trade-offs.

✔️ Ultrasonic cool-mist humidifiers: These popular models use a vibrating plate to turn water into a fine mist that's released into the room. They're typically compact, energy-efficient, and extremely quiet, making them a smart choice for bedrooms, nurseries, and other spaces where noise matters.

Many ultrasonic humidifiers are also affordable, with basic models costing less than $50. One drawback is that minerals in tap water can be dispersed into the air, leaving a fine white dust on nearby surfaces. Our experts recommend using distilled water, especially if you have hard water at home. Regular cleaning is also essential to prevent bacteria and mold from building up inside the tank.

✔️ Evaporative humidifiers: Instead of producing a visible mist, evaporative models use a fan to draw air through a wet wick or filter, allowing moisture to evaporate naturally into the room. One big advantage is that evaporative humidifiers are less likely to leave moisture on surrounding furniture or floors. They also generally release fewer minerals into the air than ultrasonic models, making them worth considering if you're concerned about white dust.

The trade-offs are noise from the fan and the need to replace the wick periodically. Some models can also be bulkier than their ultrasonic counterparts. Still, our experts often recommend evaporative models for anyone who wants consistent humidity without a visible cloud of mist.

✔️ Warm-mist humidifiers: Also called steam vaporizers, these machines use a heating element to boil water before releasing moisture into the air. The heating process can reduce microorganisms in the water, though it doesn't eliminate the need for regular cleaning.

Warm-mist humidifiers can be comforting during colder months, but they generally consume more electricity than cool-mist models. More importantly, hot water and steam create a burn hazard, so our experts advise against using them in nurseries or anywhere young children and pets could knock them over.

✔️ Whole-house humidifiers: If dry air is a problem throughout your home, a whole-house system might be worth considering. Unlike portable humidifiers, which treat one room or area at a time, these systems are designed to maintain humidity across multiple rooms.

Some whole-house humidifiers connect directly to a home's existing heating and cooling system, automatically adding moisture as air circulates. Others are large portable console units that can serve several rooms, depending on the layout.

Ducted whole-house humidifiers typically connect to your home's water supply, eliminating the need for constant refilling. Freestanding console models are easier to set up and don't require professional installation, but you'll still need to refill their water tanks regularly. Both options can make sense for homes dealing with persistent dryness across multiple rooms.

Our experts in the Home Improvement & Outdoor Lab evaluate humidifiers throughout the year, with testing ramping up ahead of the colder months. Product analysts regularly survey the marketplace to identify models consumers are most likely to encounter online and in stores. Over the past decade, our engineers have evaluated dozens of humidifiers, including 25 models in our most recent review.

Hands-on testing begins in our Lab, where we measure each humidifier's moisture output, water-tank capacity, and run time. To evaluate performance, our engineers use a humidity-controlled chamber to measure how long each humidifier takes to reach set humidity levels. We also measure energy consumption and assess sound levels, since even an effective humidifier can be a nuisance if it's too loud to run while sleeping.

Ease of use is another major consideration, both in the Lab and during extended evaluations in the homes of consumer testers. Our experts assess how simple each humidifier is to fill, operate, and clean, paying close attention to tank openings, controls, and portability. We also evaluate convenience features like automatic shutoff, built-in humidity sensors, and smart connectivity to determine whether they offer meaningful benefits in everyday use.

Choosing the right type of humidifier is a good starting point, but several other factors determine how well a model will work in your home. Here's what our experts recommend considering before buying.

✔️ Size and coverage: A humidifier needs enough moisture output to handle the space where you'll use it. Manufacturers typically list a recommended coverage area in square feet, so start by measuring your room's length and width, then multiply the two numbers. For example, a 12”-x-15” bedroom measures 180 square feet, so there's no need to buy a model designed for a massive living room. On the other hand, a compact tabletop humidifier may struggle in a large, open floor plan.

Coverage ratings are useful for narrowing your options, but they're not a guarantee of performance. Ceiling height, air circulation, and how dry your home is can all affect how much moisture you'll need. Our experts also recommend comparing moisture output, typically measured in gallons or liters per day, rather than relying on tank size alone.

✔️ Humidity control: Maintaining the right moisture level is essential. According to the Environmental Protection Agency, indoor relative humidity should generally stay between 30% and 50%. Too little moisture can lead to dry skin and irritated nasal passages, while too much can encourage mold and dust mites.

The best humidifiers have a built-in humidistat that monitors humidity levels and automatically adjusts or shuts off the machine when the desired setting is reached. That helps prevent over-humidifying a room, particularly overnight.

If your humidifier doesn't include a humidity sensor, consider picking up an inexpensive hygrometer to monitor the room's moisture level separately.

✔️ Water-tank capacity: Tank size determines how frequently you'll need to refill the humidifier. Smaller models can require refilling after several hours of use, while larger tanks may run for a full day or longer on a low setting.

For bedrooms, our experts recommend looking for a model that can operate through the night without running dry. Keep in mind that advertised run times are often based on the lowest mist setting, so a humidifier operating at full output will need water more frequently.

An automatic shutoff feature is especially useful because it stops the machine when the tank runs empty. A translucent tank also makes it easier to see when a refill is needed.

✔️ Ease of cleaning: Humidifiers need more frequent maintenance than many other household appliances, so tank design is a major consideration. Models with wide openings are much easier to scrub than those with narrow necks and hard-to-reach corners.

Our experts especially like top-fill designs and removable tanks that fit comfortably in the sink. Dishwasher-safe components can be another time-saver, provided the manufacturer specifically approves them for machine washing.

Be sure to check whether the humidifier requires replacement filters, wicks, or demineralization cartridges. Those components add to the cost of ownership, and some require replacement several times a year.

✔️ Noise: If your humidifier will run in a bedroom or nursery, pay attention to how much noise it produces. Ultrasonic models tend to be among the quietest because they don't rely on a fan to disperse moisture. Evaporative models, meanwhile, produce a steady fan sound that some people find soothing and others find distracting.

Our Lab testing evaluates noise alongside moisture output, since a machine that performs well but keeps you awake isn't much use in a bedroom. Sleep modes and dimmable displays are helpful extras for light sleepers.

✔️ Energy efficiency: Most portable cool-mist humidifiers use relatively little electricity, though consumption varies by size and technology. Warm-mist models generally use more energy because they heat water to produce steam.

When comparing models, check the wattage rating. For example, a 20-watt humidifier running eight hours a night for 30 days would use approximately 4.8 kilowatt-hours of electricity. Your actual cost will depend on local utility rates and the machine's operating settings.

Don't overlook ongoing expenses either. Replacement filters and distilled water can add up, particularly if you run the humidifier daily throughout the winter. A low purchase price isn't always the best long-term value.

✔️ Convenience and safety: Features like automatic shutoff, adjustable mist settings, and a built-in humidistat are worth prioritizing. Wi-Fi connectivity, app controls, and voice-assistant compatibility can make operation more convenient, but they're generally extras rather than necessities. For homes with babies, young children, or pets, our experts recommend cool-mist models to avoid the burn risks associated with hot water and steam. Look for a stable base and make sure the power cord can be kept out of reach. Some humidifiers also feature aromatherapy compartments, but never add essential oils directly to the water tank unless the manufacturer specifically allows it. Be especially cautious with essential oils around children and pets.

Humidifiers increase the amount of moisture in indoor air, helping bring relative humidity back into a more comfortable range. Relative humidity is simply the amount of water vapor in the air compared with how much that air can hold at a given temperature. When cold outdoor air enters your home and gets heated, its relative humidity typically drops, which explains why indoor air often feels especially dry during winter.

Portable humidifiers restore moisture using one of three basic methods. Ultrasonic models create a fine mist through rapid vibrations. Evaporative humidifiers use a fan to move air through a wet wick, allowing moisture to enter the air naturally. Warm-mist models heat water to produce steam.

Regardless of the technology, the goal is the same: maintain enough moisture in the air to reduce dryness without creating damp conditions.

A humidifier can help ease discomfort from dry nasal passages, lips, and skin, but it's not a cure for colds, allergies, or other respiratory conditions. A standard humidifier adds moisture to the air but doesn't filter out airborne particles like dust, pollen or pet dander. If that's your goal, consider an air purifier or a combination air purifier and humidifier.

For most homes, a relative humidity level between 30% and 50% is the goal. If you notice condensation collecting on windows or damp spots around the humidifier, reduce the output or turn the machine off.

Keeping a humidifier clean is essential, since standing water creates conditions where bacteria and mold can grow. Good Housekeeping's Institute Cleaning Lab experts recommend cleaning your humidifier at least once a week, or more frequently with daily use. For added precaution, the EPA recommends cleaning portable humidifiers every three days, along with emptying, drying, and refilling the tank daily.

Start by unplugging the humidifier and emptying any remaining water from the tank. Wipe the interior dry before refilling it with fresh water. Avoid topping off old water, since that allows contaminants to accumulate over time.

Every few days, remove the tank and other washable components according to the manufacturer's instructions. Use a soft brush or sponge to remove mineral deposits and any film that has formed on the interior surfaces. White vinegar can help dissolve mineral buildup. The EPA suggests a 3% hydrogen peroxide solution when the manufacturer doesn't specify a cleaning product. Always follow your humidifier's cleaning instructions, never mix cleaning chemicals, and rinse thoroughly to prevent residue from being dispersed into the air.

Pay attention to filters and wicks, too. Some can be rinsed or cleaned, but others need to be replaced rather than washed. Follow the instructions for your particular model, since cleaning a disposable wick can damage it and reduce performance.

Finally, don't forget about the water itself. Distilled water is generally the best choice for ultrasonic humidifiers, since it contains fewer minerals than tap water and helps prevent the white dust that can settle on furniture.

At the end of the season, give the humidifier one last cleaning, let all components dry completely, and store it in a clean, dry location. Proper maintenance helps keep the machine working efficiently and prevents unpleasant surprises when you take it out again next winter.

Why trust Good Housekeeping?

The Good Housekeeping Institute's Home Improvement & Outdoor Lab has evaluated dozens of humidifiers over the past decade, including 25 models in its latest review. Our testing combines controlled performance measurements with hands-on evaluations of cleaning, noise, energy use and everyday operation.

Contributing Writer Timothy Dahl wrote this guide. He has spent the past two decades reviewing home comfort products, including humidifiers, dehumidifiers, and air purifiers, as well as power tools and other household essentials.

This guide draws on the Good Housekeeping Institute's published humidifier testing and reporting, including work by Dan DiClerico, director of the Home Improvement & Outdoor Lab, who has covered humidifiers and other home appliances for more than 25 years. We've also incorporated guidance from the Environmental Protection Agency and other recognized health and safety organizations.