Coverage

How much coverage a humidifier provides is one of the most crucial factors when choosing a model for your home. You need one that matches up well with your square footage. If you buy one that is meant for a large home and you live in a small apartment, you run the risk of overhydrating the air, which can encourage the growth of mold. But if you buy one that is too small for your large home, you won’t be putting enough moisture in the air, which means it may help a little but you won’t get the full benefits.

Before selecting a humidifier, you’ll need to know the square footage of the room you’re going to place it in. Here are some of the ranges you may see.

• Up to 25 square feet: You’ll notice the occasional travel humidifier on the market when you’re looking at the various models available. If you travel frequently and have a problem with the dry conditions in some hotels, this type of humidifier can be placed near your bed in a hotel room.
  
• Up to 299 square feet: These types of humidifiers generally are seen in a bedroom to help a person breathe moisturized air while they sleep. If someone in your home suffers from occasional nose bleeds or is fighting a cold, this size humidifier will come in handy. It can be moved from room to room with ease.
  
• Up to 499 square feet: This next size is a step up, so it will require additional space. If you have a medium-sized room, this is a good bet, but it will be overkill for most bedrooms.
  
• Up to 999 square feet: Made for large rooms, a humidifier with this capability will be too big for most people’s bedrooms, but it would be great in a big game room or basement. If you have seriously dry air or a big house, you may want a unit of this size.

Tank Capacity

When you’re putting moisture into the air, it needs to come from somewhere. The water tank on the humidifier will supply the moisture needed for the air, but you’ll have to fill up the tank whenever that water source is depleted. That means, ideally, you’ll have a fairly sizable tank so you aren’t having to frequently fill it up. A humidifier with a small tank that runs on the highest setting may be dry in the morning if you turn it on before heading to bed, while a humidifier with a large tank running on the highest setting may not need to be filled up for several nights.

You should also keep in mind that the bigger the tank, the more room you’ll need for placing and storing your humidifier when it isn’t in use. You’ll be able to find a large variety of tank capacities, so you should give careful thought as to whether you want a portable humidifier or one that weighs more and will likely remain in the same place all the time. Here are some of the tank sizes you’ll encounter.

• 2 liters: Some tanks only hold this much water, and this size is most appropriate for a bedroom. It will need to be filled almost daily if it’s run on the highest setting overnight.
  
• 4 liters: If you want a humidifier for your larger living room, this is a decent tank size for that. It won’t take up a huge amount of space and you won’t need to fill it daily.
  
• 6 liters: This size of water tank is still portable, so if you’re buying one to move from room to room in a home, this is an excellent choice.
• 16 liters: While smaller humidifiers can be placed on a dresser or nightstand, a humidifier with this large of a tank is generally a floor unit and will be best suited for use on a non-carpeted floor.

Mist Output

Some rooms only need a little moisture to become more comfortable and properly hydrated. Some other rooms need a lot of extra moisture to reach proper levels. You’ll know your humidity level is likely too high if you begin to see condensation on the windows or if your walls begin to feel moist to the touch. If your humidity levels are too low, your lips may look cracked and you might feel like your mouth, throat, and skin is constantly dry.

Humidifiers come with a range of mist output levels, from low to high, and there are also specialized cool mist humidifiers that provide all the benefits of a traditional humidifier with the added element of a cooling effect for the hotter months. To help take the guesswork out of which mist output setting you should be using, some humidifiers allow you to set the humidity percentage you want and the mist output will automatically adjust to make that happen. If your humidifier doesn’t include a percentage you can set it for, you might want to buy an inexpensive hygrometer you can use to ensure your room is properly hydrated. If you want to have the ideal level of humidity in the air, watch the temperature outside and set the mist output accordingly since the outdoor temperature can affect what indoor humidity level is most appropriate.

• Outside temperature of 20 to 40 degrees: Depending on how dry your room is, you may need to crank your mist output on high to reach an ideal humidity of up to 40 percent.
  
• Outside temperature of 10 to 20 degrees: You should stick with a humidity level of no higher than 30 percent, which might require a medium mist output setting.
  
• Outside temperature of -10 to 0 degrees: For super cold temperatures, you should set your humidifier on the low mist output setting because you don’t want your humidity higher than 20 percent.

Continuous Use

Some people run their humidifiers all the time, while others only run them at night or during the hours they are home. Running it during the night can be helpful because it can cut back on your snoring so you rest better, and it can allow you to wake up without a dry sinus feel. If you work away from home, you may want to turn off your humidifier when you’re gone and then run it on high to moisturize the air when you get home. Running a humidifier continuously can result in an environment that is too moist, so it’s generally best to run it only for 8 to 12 hours per day unless you have a breathing issue that requires moist air all the time.

If you choose to run your humidifier continuously, you’ll need to know how long it can run before the tank runs out of water. Many humidifiers feature an automatic shutoff that will protect your device if the tank goes dry while it’s still running. Knowing how long each tank might last you while using it continuously can help you plan better about how often you’ll need to fill it.

• Two liters: If you buy a humidifier with a tank size of two liters, you can expect to fill it every 8 to 10 hours if you use it continuously, even if you have it on the low mist output setting.
  
• Six liters: On the lowest setting, you’ll have to fill this humidifier every 24 hours or so if you plan to run it continuously.
  
• 16 liters: If you opt for a large humidifier, you won’t have to refill it as often on the lower setting. But you should still plan to check and fill it every three days or so, to be on the safe side.

Type

Humidifiers come in many different types, and they all have their sets of advantages and disadvantages. To help you make an informed decision, you’ll need to understand what types of humidifiers are available and if they would be a good fit for your household. Here are the types of humidifiers you’ll see and some information you’ll need to know about each type.

• Central humidifiers: This kind of humidifier is permanently set up in your home through the heating and air conditioning systems. While this type will humidify the whole house, they are more expensive to install and much more complicated than a plug-in standalone unit.
  
• Ultrasonic humidifier: These humidifiers use ultrasonic vibrations to produce a mist. They are easy to use, and many of them also contain a built-in nightlight. While most of these are cool-mist humidifiers, occasionally, you’ll see some that also produce warm mist. If you’re using a humidifier in a house with children or pets, you should only ever use a cool-mist humidifier because that will eliminate the risk of scalding.
  
• Impeller humidifiers: This type uses a spinning disc to create water droplets that are released into the air to hydrate it. Since the mist they create is cool, these are also a suitable choice for your child’s bedroom or if you have curious pets.
  
• Evaporator Humidifier: This type uses a fan to speed up the process of evaporation. It creates a cool mist, and while it is generally less expensive to buy than ultrasonic models, it often requires filter maintenance.
  
• Steam humidifiers: Steam humidifiers are also commonly called warm-mist humidifiers. Warm steam can feel soothing in the winter, and often these units are quieter than cool-mist humidifiers, with the exception of whisper-quiet ultrasonic models. The main drawback to this type is that if you use them around small children and pets, they can be badly burned by them.