What Humidity Should My House Be? Ideal Levels by Season
Too dry and the air feels harsh and wood cracks. Too damp and mold and musty smells move in. The right number depends on the season, and you can measure it for less than the cost of lunch.
Quick answer
Keep indoor relative humidity between 30 and 50 percent, as the EPA recommends, and always below 60 percent. In cold weather aim for the lower end, roughly 30 to 40 percent, so windows do not fog. In summer, air conditioning and dehumidifiers usually keep it in range; basements may need a dehumidifier set to about 50 percent.
- Difficulty
- Easy DIY
- Ideal range
- 30 to 50% relative humidity
- Upper limit
- Below 60% (EPA)
- Winter target
- About 30 to 40%, lower in deep cold
- Measure with
- A digital hygrometer
On this page
Relative humidity is the amount of water vapor in the air compared with the most it could hold at that temperature. At 50 percent, the air holds half its maximum. Because warm air can hold more water than cold air, the same moisture reads as a lower relative humidity when you heat it, which is why indoor air gets so dry in winter.
The recommended range
The EPA recommends keeping indoor humidity below 60 percent, ideally between 30 and 50 percent. Within that band, most people are comfortable, mold has a hard time growing, and wood floors and furniture stay stable.
| Situation | Target | Why |
|---|---|---|
| Year-round ideal | 30 to 50% | EPA recommendation for comfort and mold prevention |
| Winter, mild (above 30°F outside) | 35 to 40% | Comfortable without fogging most double-pane windows |
| Winter, cold (10 to 30°F) | 30 to 35% | Keeps condensation off double-pane glass |
| Winter, very cold (below 10°F) | 25 to 30% | Lower limit set by your windows; see the table in our condensation guide |
| Summer | 40 to 50% | Air conditioning removes moisture as it cools |
| Basement | Below 60%, ideally about 50% | Cool surfaces and soil moisture encourage mold |
In winter, your windows set the practical ceiling. Our window condensation calculator shows the highest humidity your glass can handle at today’s outdoor temperature.
Signs your humidity is off
Too low (under about 30 percent): static shocks, dry skin and lips, scratchy throat, gaps opening between floorboards, cracking wood furniture and musical instruments going out of tune.
Too high (over about 50 to 60 percent): condensation on windows, musty smells, mildew in bathrooms and closets, peeling paint, damp spots on walls and a clammy feeling even when the air is cool.
How to measure it
A digital hygrometer, often sold as an indoor thermometer and humidity monitor, costs about $10 to $20. Many smart thermostats show humidity too. Put the hygrometer in a central living area away from bathrooms, the kitchen and direct sun, and check it at different times of day.
Check your hygrometer with the salt test
Air sealed above a damp salt slurry settles at about 75 percent relative humidity, a fixed point used to calibrate humidity sensors.
- Make a damp salt paste.
Put a few tablespoons of table salt in a bottle cap or small dish and add just enough water to make it look like wet sand. It should not dissolve.
- Seal it with the hygrometer.
Put the dish and the hygrometer together in a zip-top bag or airtight container. Keep it at steady room temperature.
- Wait 8 to 12 hours, then read it.
A perfect hygrometer reads 75 percent. If yours reads 71, add 4 points to its readings from now on.
How to lower humidity
- Run bathroom fans during and after showers and the range hood while cooking.
- Use a dehumidifier in damp rooms and basements; ENERGY STAR models remove the same moisture with less electricity.
- Make sure the clothes dryer vents outdoors and avoid drying laundry inside.
- Fix leaks, clear gutters and grade soil so water drains away from the foundation.
- In summer, run the air conditioner; it dehumidifies as it cools. An oversized unit that short-cycles removes less moisture.
How to raise humidity
- Use a portable humidifier in bedrooms, set to about 35 to 40 percent, and clean it as the manufacturer directs to prevent mold and bacteria.
- If you have a whole-house humidifier on your furnace, lower its setting as outdoor temperatures drop to avoid wet windows.
- Seal air leaks. Cold outdoor air that leaks in becomes very dry when heated; a tighter house holds humidity better.
Frequently asked questions
Is 60 percent humidity too high indoors?
It is at the limit. The EPA recommends keeping indoor humidity below 60 percent, ideally between 30 and 50, because persistent dampness above that level encourages mold and dust mites.
Is 25 percent humidity too low?
It is drier than the recommended range, and many people notice static shocks, dry skin and irritated eyes. In very cold weather, though, it may be all your windows can handle without condensation. A humidifier set to 30 to 35 percent is a reasonable compromise.
What humidity should a basement be?
Below 60 percent, and ideally around 50. Basements run damp because they are cool and surrounded by soil. A dehumidifier with a built-in humidistat set to about 50 percent, draining to a floor drain or pump, keeps most basements dry.
How accurate are cheap hygrometers?
Many inexpensive digital hygrometers are accurate to within a few percentage points, which is good enough for home use. You can check yours with the salt test described in this guide.
Sources
- A Brief Guide to Mold, Moisture and Your Home U.S. Environmental Protection Agency
- Moisture Control U.S. Department of Energy, Energy Saver (archived copy, 2025)
- What Humidity Should My House Be At? Carrier
- Dehumidifiers ENERGY STAR (U.S. EPA)
First published October 6, 2026. Last reviewed October 6, 2026. Spot an error? Tell us and we will check it against the source.