What is the difference between a humidifier & a dehumidifier?

Updated February 21, 2017

Keeping proper air moisture inside your home is a delicate balance. Too much or too little moisture can cause health problems, as well as problems for the structure of your home itself. The air where you live may naturally be too low or too high in humidity, but a humidifier or dehumidifier can help solve the problem and make your home a comfortable place to live.


A humidifier is a machine that adds moisture to excessively dry air. It works by taking water from a holding tank (which you fill) and adding it to the air as a mist, increasing the overall moisture content of the air in your home.

Dry Air

If the air is too dry, a home can benefit from the use of a humidifier. Dry air can cause problems such as frequent illnesses or infections, nosebleeds, sore throats, dry skin, excessive static electricity, and shrinking or cracking of wood fixtures in the home.


A dehumidifier is a device that takes excess moisture out of the air. The machine takes in air on one side, where the air comes into contact with cold tubes. Moisture from the air collects on the cold tubes and drips into a container. The dry air is put out the other side of the machine, and the air in your home is made a bit drier.

Moist Air

A dehumidifier is beneficial for a home with an excess amount of moisture in the air. This can happen in homes near large bodies of water or in areas where the climate is typically more humid. Excess moisture in the home can cause problems such as mould, allergies, respiratory issues and fungal skin infections.

Your Home's Needs

The humidity in your home should ideally be between 30 per cent and 50 per cent (this can be measured with a device called a hygrometer). If the humidity is significantly above or below those marks, it may indicate that you need either a humidifier or a dehumidifier. Improving the air quality in your home can make it a much more enjoyable space for living.

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About the Author

Beth Wankel is currently working as a freelance writer, editor and as a parenting blogger. She holds a bachelor's degree in English, with a minor in print journalism from the University of Wisconsin-Eau Claire. She has several years of professional writing and editing experience, namely web writing. Wankel resides in San Francisco with her husband and young son.