The short answer
If your hygrometer reads below about 35 percent, a humidifier helps; above about 55 percent, a dehumidifier does. Many homes need both: a humidifier in winter bedrooms and a dehumidifier in a summer basement.
Signs of dry air
- Static shocks, dry skin and lips, scratchy throat in the morning
- Gaps opening in wood floors and trim
- Hygrometer below 30-35 percent in winter
Signs of damp air
- Musty smell, condensation on windows or cold pipes
- Mold spots in corners, closets or the basement
- Hygrometer above 55-60 percent
What each does
| Humidifier | Dehumidifier | |
|---|---|---|
| Does | Adds water vapor | Removes water from the air |
| Typical use | Winter bedrooms, dry climates | Basements, humid summers, crawlspaces |
| Helps with | Dry skin, irritated airways | Mold, dust mites, musty smells |
| Upkeep | Daily refills, weekly cleaning | Emptying or draining, filter rinse |
Products mentioned
Questions readers ask
Can a dehumidifier help with allergies?
Yes, if dust mites or mold are the trigger; keeping humidity below 50 percent limits both.
Should I run a humidifier and a dehumidifier together?
Not in the same room; use each where its reading calls for it.