How to Stop Condensation on Windows (Inside Your Home)

Quick answer: To get rid of condensation on windows, lower indoor humidity and warm up the glass. Run bathroom and kitchen exhaust fans, stop drying laundry indoors, turn down any humidifier, and use a dehumidifier to keep humidity around 30–40% in cold weather. Open blinds and curtains so warm room air reaches the glass. Fog between double panes means a failed seal, which only a glass replacement fixes.

Waking up to dripping windows every winter morning is more than a nuisance. That water soaks into sills and trim, peels paint, and feeds black mildew in the corners of the frame. This guide explains how to get rid of condensation on windows by fixing the cause instead of wiping the glass every day, and how to tell when the problem is the window itself.

Why do my windows get condensation on the inside?

Condensation happens when warm, moist air touches a surface colder than its dew point. The air can’t hold its water vapor at that temperature, so the vapor turns into droplets. In winter, your windows are the coldest surfaces in the room, so they’re where moisture shows up first.

Two things control how bad it gets:

• How much moisture is in your indoor air. Showers, cooking, breathing, houseplants, pets, aquariums, and drying clothes all add water vapor. Everyday living for a family can easily add a gallon or more of water to indoor air each day.
• How cold the glass is. Single-pane glass, old aluminum frames and windows covered by heavy drapes get very cold. The colder it is outside, the lower your indoor humidity has to be to stay dry.

That’s why condensation is often worst on the coldest mornings, in bedrooms (people breathe out moisture all night with the door closed), and in kitchens and bathrooms.

Inside, outside, or between the panes?

• Inside the room: too much indoor humidity for the glass temperature. This guide fixes it.
• Outside the glass: usually on cool, humid mornings in spring or fall. It’s a sign your windows insulate well, since the outer pane stays cold. It’s harmless and burns off as the sun warms the glass.
• Between the panes: the seal on an insulated glass unit has failed, letting moist air in. No amount of dehumidifying fixes it. The glass unit (not always the whole window) needs replacing, and it’s worth checking whether your window warranty covers it.

What indoor humidity stops window condensation?

The EPA recommends keeping indoor humidity between 30% and 50%. In winter, though, 50% is often too high for windows to stay dry. University extension programs in cold states publish guidelines that lower the target as outdoor temperatures drop. A widely used version looks like this:

Outdoor temperature	Suggested maximum indoor humidity
20°F to 40°F	About 40%
10°F to 20°F	About 35%
0°F to 10°F	About 30%
-10°F to 0°F	About 25%
-20°F to -10°F	About 20%

These are general guides for typical double-pane windows. If your windows still fog at these levels, they’re running cold, and the airflow and window upgrades below help.

How to get rid of condensation on windows: step by step

1. Measure your humidity. Put a digital hygrometer in the room with the worst windows, away from the glass and any heat source. Check it morning and evening for a few days. This tells you how far you need to bring humidity down.
2. Dry the windows and sills right away. Wipe water off glass and sills each morning with a microfiber cloth or a small squeegee. Standing water on wood sills is what leads to rot and mildew.
3. Use your exhaust fans properly. Run the bathroom fan during every shower and for about 20 minutes afterward. Run the kitchen range hood whenever you boil, simmer or use the dishwasher’s dry cycle. Make sure both fans vent outside, not into the attic.
4. Cut the big moisture sources. Stop drying laundry on racks indoors, confirm your dryer vents outside, and cover pots while cooking. Move large groups of houseplants away from cold windows and cover aquariums. Store firewood outside, since green wood releases a lot of moisture.
5. Turn down or turn off humidifiers. Whole-house humidifiers on furnaces are a very common cause. Set them to match the outdoor-temperature table above, and turn down portable humidifiers, especially in bedrooms.
6. Run a dehumidifier. If humidity stays above your target after the steps above, a dehumidifier pulls the extra water out. Set it to your winter target, often 35–40%, and let it run in the dampest area, usually the basement or the room with the worst windows.
7. Let warm air reach the glass. Open blinds and curtains during the day, and leave a gap at the bottom at night. Don’t block heating registers under windows with furniture or drapes. A ceiling fan on low, set to push air up and down the walls, helps too.
8. Air out the house briefly. On dry winter days, opening a couple of windows for 5–10 minutes swaps humid indoor air for cold, dry outdoor air. It’s quick and cheap, and it works best right after showering or cooking.
9. Seal and insulate the window. Add weatherstripping where you feel drafts and caulk gaps around trim. For single-pane or drafty windows, clear plastic window insulation film kits or interior storm windows create a warmer inner surface, which cuts condensation sharply.
10. Clean any mildew on frames and sills. Scrub black spots with warm water and dish soap, or undiluted white vinegar on painted wood, then dry completely. Check caulk and replace any that has turned black.

If you use a bleach solution on mildewed window frames or tile sills, wear rubber gloves and eye protection, open a window for ventilation and keep kids and pets away until surfaces dry. Never mix bleach with ammonia, vinegar or other acidic cleaners, which releases toxic gases. Follow the label, and test on a hidden area first because bleach can discolor wood and vinyl.

The equipment that helps

Most window condensation is a humidity problem, so the right tools measure humidity and remove it. For a full lineup of options by room and budget, see our guide to the best dehumidifier for basement moisture, or our best small dehumidifier roundup for single rooms.

A quick note on the tiny thermoelectric “mini dehumidifiers” sold for windows: they remove only ounces of water a day. They can’t lower humidity in a bedroom enough to stop window condensation. For this job, a compressor unit is the one that works.

Compressor dehumidifiers slow down in cold spaces below about 65°F, where their coils can frost. In a very cold basement, choose a model with auto defrost and keep the space reasonably warm.

How to keep condensation from coming back

• Adjust humidity with the weather. Lower your target as outdoor temperatures drop, using the table above. What’s fine in November can cause dripping windows in January.
• Make fans automatic. A humidity-sensing or timer switch on the bathroom fan makes the 20-minute rule effortless.
• Keep air moving. Open curtains daily, keep registers clear, and don’t push beds or dressers tight against windows.
• Check the dryer vent and gutters. A disconnected dryer duct or overflowing gutters can dump moisture into walls and crawl spaces that ends up in your indoor air.
• Dry out the basement and crawl space. Damp foundations feed humidity into the whole house. If your basement smells musty, our guide on how to get rid of musty smell in basement areas helps.
• Plan window upgrades. When you replace windows, low-E double- or triple-pane glass with warm-edge spacers keeps the inner pane warmer and far less likely to fog.

Condensation also lands on other cold spots: exterior closet walls, corners behind furniture, and bathroom ceilings. If you’re seeing mildew in those places, see how to get rid of mold smell in closet spaces and our complete guide to mold and mildew.

When to call a professional

Call a window contractor if you see fog or moisture between the panes of double- or triple-pane glass (a failed seal), if sills or frames feel soft or show rot, or if water runs down the wall below the window. Call a mold remediation professional if mold covers more than about 10 square feet (the EPA’s guideline), shows up inside walls, or returns quickly after cleaning. An HVAC technician can check whole-house humidifier settings and ventilation if humidity stays high despite your efforts. See a doctor if anyone has breathing symptoms that seem linked to mold.

Already seeing black spots? Follow how to get rid of mold on window sills to clean them safely and keep them from coming back.

Frequently asked questions

Is condensation on windows bad?

Occasional light fog that clears by mid-morning is common and harmless. Daily heavy condensation that runs onto sills is a problem. The water can rot wood frames, peel paint, damage drywall below the window, and feed black mildew. It’s also a sign that indoor humidity is high enough for mold to grow on other cold surfaces in the house.

Does a dehumidifier stop window condensation?

Yes, when the cause is high indoor humidity, which it usually is. A compressor dehumidifier set to around 35–40% in winter removes enough moisture for glass to stay dry in most homes. It won’t fix fog between panes, and very cold single-pane windows may still fog, so pair it with insulation film or storm windows.

Why do my windows only sweat in the bedroom?

Bedrooms get a lot of moisture from breathing overnight, often with the door closed and curtains drawn over the glass. That traps humid air against a cold window. Leave the door open a few inches, open the curtains slightly, and turn down any bedroom humidifier. A small compressor dehumidifier can help in a room that stays damp.

Should I open windows to stop condensation?

Briefly, yes. On a cold, dry day, opening a couple of windows for 5–10 minutes replaces humid indoor air with dry outdoor air, which cuts condensation quickly. Leaving windows cracked all day in winter wastes heat and isn’t necessary. A timer-driven exhaust fan or a dehumidifier gives the same benefit without the drafts.

How do I fix condensation between double-pane windows?

Fog between the panes means the seal on the insulated glass unit has failed and moist air has gotten inside. You can’t fix it by lowering indoor humidity. A glass shop can usually replace just the sealed glass unit rather than the whole window. Check your window warranty first, because seal failures are often covered.

Does condensation on the outside of windows mean a problem?

No. Exterior condensation forms on cool, humid mornings when the outer pane is colder than the dew point. It actually shows your windows insulate well, because heat from inside isn’t warming the outer glass. It evaporates as the sun and air warm up and doesn’t need any fix.

The bottom line: dry windows come from lower indoor humidity and warmer glass. Start with fans and moisture sources, measure, then add a dehumidifier if you need it. To choose one, see our guide to the best dehumidifier for basement and whole-floor humidity.