Buying Guide

How to Choose a Humidifier and Dehumidifier

Humidifier Size

To make the most of your humidifier, choose one based on the size of the room you’ll use it in.  

Small Rooms (less than 400 square feet)

Small room humidifiers (aka "portable" or "compact" humidifiers):

  • Can be used on for tabletops (check manufacturer's safety warnings)
  • Plug directly into wall
  • Use refillable water tank
  • Lightweight
Medium Rooms (400-1,000 square feet)

Medium room humidifiers (sometimes called tower humidifiers):

  • Water tank requires less refilling than tabletop units
Large rooms (more than 1,000 square feet)

Large room humidifiers (aka console or tower humidifiers):

  • Use larger refillable water tank
  • Humidify several rooms
  • Not lightweight but can still be moved throughout home
Whole house

Whole house humidifiers (aka in-duct or online humidifiers):

  • Introduce moisture directly into a forced air heating system
  • Carry moist air to every room
Humidifier Designs

Cool mist, warm mist, vaporizers, ultrasonic and cool mist impeller humidifiers all boost the humidity with different methods. 


Evaporative humidifiers: 

  • A fan blows dry air through a wick, which absorbs water from a refillable tank or the household water supply
  • Cool water from the wick evaporates into the air, boosting the humidity level; wick filters impurities out of the water
  • Common design for tabletop, console and whole-house units
  • Must refill water tank 1-2 times a day and replace wick every 2 months
  • Relatively low power demands
Warm Mist / Steam Humidifiers
Warm mist

Warm mist aka steam humidifiers:

  • Works like a tea kettle: heating element boils water from a refillable tank or household water supply, generating steam that humidifies surrounding air
  • Removes impurities from the water, producing clean saturated air
  • Steam helps keep rooms warm
  • Quiet operation
  • Water tank must be filled periodically, but there’s no wick to replace
  • May be necessary to clean unit regularly, as impurities from water can build up in the tank

Tip: Vaporizers are small, low-output warm mist humidifiers. They have a built-in water reservoir, rather than a removable tank.

Ultrasonic Humidifiers

Ultrasonic humidifiers: 

  • A metal diaphragm vibrates at ultrasonic frequencies to break up water into a cloud of tiny droplets
  • Does not filter water, but demineralization cartridges can be added, as can heating options
  • Used in many tabletop models
  • Very quiet with relatively low power demands
  • Tank must be refilled regularly, but there is no filter to replace
Cool Mist Impeller Humidifiers
Cool mist impeller

Cool mist impeller humidifiers:

  • A spinning disc generates a fine mist of cool water
  • Does not filter water, so distilled water is recommended
  • Quiet; doesn’t use much power
  • No need to be refilled, and no filters to replace; clean tank regularly
Dehumidifier Size

Like humidifiers, choose your dehumidifier based on the size of the room.  

Portable Dehumidifiers
Portable dehumidifiers

Portable dehumidifiers:

  • Work the same basic way as a window air conditioning unit: Fan blows moist air from the room across cold refrigerant-filled coils, which cool the air, causing the moisture to condense into water droplets. The water collects in a bucket, which needs to be emptied periodically.
  • Many models have a hose attachment that lets you drain the water directly into a sink or basement drain
  • Includes a separate heating coil that warms the air again before expelling it into the room
Whole House Dehumidifiers
Whole house dehumidifiers

Whole house dehumidifiers:

  • Work the same basic way as portable models, but with extra power necessary to dehumidify several rooms at once
  • Empty collected water into a drain leading outside the house rather than a refillable bucket
  • Good for use in spaces up to 3,000 square feet
  • Some models connect to ductwork in a forced air heating system; others are self-contained systems
Deciphering Humidifier & Dehumidifier Lingo

Before purchasing, understand your new unit’s tank capacity, run time and features.


Output per day: standard measure of a humidifier’s power, which determines how many rooms it can humidify. Some models may include a square footage or room number recommendation on the label.

  • Tank capacity: amount of water the refillable tank can hold, listed in gallons. Typically, you need to?refill larger tanks less frequently than smaller tanks. 
  • Run time: how long the humidifier can run on a full tank of water.

Compact Humidifier

Typical Output Range: 0.5-1.5 gallons per day

Suggested Application: Humidifying single, small room

Tabletop Humidifier

Typical Output Range: 2-4 gallons per day

Suggested Application: Humidifying single room

Tower Humidifier 

Typical Output Range: 2-4 gallons per day

Suggested Application: Humidifying single room

Small Console Humidifier

Typical Output Range: 6-8 gallons per day

Suggested Application: Humidifying 2-3 rooms

Large Console Humidifier

Typical Output Range: 9+ gallons per day

Suggested Application: Humidifying entire floor in a large house or all rooms in a small to medium size house (2,500- 3,000 square fee

Whole-house humidifier

Typical Output Range: 9+ gallons per day

Suggested Application: Humidifying all rooms in a medium size house (3,000-4,000 square feet)


  • Capacity: standard rating for dehumidifier power, which indicates the moisture level and room size the unit can handle.
  • Drain hose connection: a connection that allows you to bypass the bucket in a portable dehumidifier and empty water into a hose leading to a drain. 
  • Automatic defrost: system saves energy by automatically shutting off the unit if frost forms on coils preventing proper operation. 
  • Multi-speed fan: a type of fan that runs at slower speeds in less humid conditions, reducing noise and energy consumption. 
  • Built-in pump: system allows you to run the drain hose up to a window, sink or elevated drain. 

Small Capacity Portable Dehumidifier

Typical Capacity Range: 25-35 pints per day 

Suggested Application: Damp Conditions in small rooms

Medium Capacity Portable Dehumidifier 

Typical Capacity Range: 40-50 pints per day 

Suggested Application: Damp conditions in medium and large rooms

Large Capacity Portable Dehumidifier 

Typical Capacity Range: 65-75 pints per day 

Suggested Application: Wet or damp conditions in large rooms

Whole-House Dehumidifier 

Typical Capacity Range: 90-140 pints per day 

Suggested Application: Wet or damp conditions in a small-to-medium size house


  • Adjustable humidistat: standard control system that automatically turns unit on and off to maintain a preset humidity level.
  • Digital display: digitally displays current relative humidity levels and settings.
  • Timer: programmable control that lets you set the humidifier to run at certain times of day.
  • Automatic shutoff: shuts off the humidifier when the tank is empty.
  • Medicine cup: feature on steam humidifiers that evaporates vapor medication.
  • Filter sensor: system that alerts you when it’s time to replace the filter.
  • Dishwasher-safe tank: a tank designed for easy cleaning in the dishwasher.
  • Safety listing: a guarantee that an independent testing agency such as Underwriters Laboratories (UL mark), Intertek (ETL mark) or the CSA Group (CSA mark) has ensured the unit is safe for its rated use.
  • ENERGY STAR ®: a label indicating that the product meets stringent energy-efficiency guidelines as outlined by the U.S. Department of Energy and the Environmental Protection Agency.
Humidifier Benefits

Using a humidifier in your home is a good way to avoid common cold-weather illnesses as moisture helps to hinder the movement of germs. 

If you're already suffering from a cold, allergies or respiratory conditions, a humidifier will make the air easier to breathe.

Adding moisture to the air also helps to reduce common conditions caused by dry weather, including:

  • Scratchy, dry throats
  • Bloody noses
  • Chapped lips
  • Dry eyes
  • Stuffy noses
  • Dry skin
  • Sinus headaches

A humidifier may make it easier for babies or children with colds to sleep as it can help reduce coughing fits.

In addition to the health benefits, using a humidifier in your home will make occupants feel a little warmer, thus reducing heating costs.