How To Buy Humidifiers and Dehumidifiers

Use the best humidifiers, whether tabletop, tower or whole-house models to regulate humidity

Humidifiers and dehumidifiers help you maintain the optimal humidity in your home to protect your home and health.

A humidifier adds moisture to the air to boost humidity back to comfortable levels, while a dehumidifier extracts moisture from the air to reduce the humidity level.

This guide explains the factors to consider so you can be confident you’re selecting the right humidifier or dehumidifier for your needs.

Tip: For most people, a relative humidity level between 40 percent to 50 percent in the summer and 30 percent to 50 percent in the winter is ideal. Low humidity can make the room feel cooler while drying out your skin and may damage furniture, while high humidity may warm up the room and spur mold and mildew growth. Substantial condensation inside your windows is a good indication humidity levels in your house are too high.

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 sq. ft.)

  • Best for tabletop (aka “portable” or “compact”) humidifiers
  • Plugs directly into wall
  • Uses refillable water tank
  • Lightweight

Medium rooms (400-1,000 sq. ft.)

  • Ideal for tower humidifiers
  • Water tank requires less refilling than tabletop units

Large rooms
(more than 1,000 sq. ft.)

  • Best for console or tower humidifier
  • Use larger refillable water tank
  • Humidifies several rooms
  • Not lightweight but can still be moved throughout home

Whole house

  • Also called in-duct or online humidifiers
  • Introduces moisture directly into a forced air heating system
  • Carries 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

  • 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”)

  • 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

  • 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

  • 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

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Dehumidifier Size

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

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

  • 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

Read on to understand your new unit’s tank capacity, run time and features.

Humidifiers

  • 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.

Category Typical Output Range Suggested Application

Compact Humidifier

0.5-1.5 gallons per day

Humidifying single, small room

Tabletop Humidifier

2-4 gallons per day

Humidifying single room

Tower Humidifier 

2-4 gallons per day

Humidifying single room

Small Console Humidifier

6-8 gallons per day

Humidifying 2-3 rooms

Large Console Humidifier

9+ gallons per day

Humidifying entire floor in a large house or all rooms in a small to medium size house (2,500- 3,000 square feet)

Whole-house humidifier

9+ gallons per day

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


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.

Dehumidifiers

  • Capacity: standard rating for dehumidifier power, which indicates the moisture level and room size the unit can handle.

Category Typical Capacity Range Suggested Application

Small Capacity Portable Dehumidifier

25-35 pints per day

Damp Conditions in small rooms

Medium Capacity Portable Dehumidifier

40-50 pints per day 

Damp conditions in medium and large rooms

Large Capacity Portable Dehumidifier

65-75 pints per day

Wet or damp conditions in large rooms

Whole-House Dehumidifier

90-140 pints per day

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


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.

Both

  • 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.