Symptom guide

Why Is My Window Foggy Between the Panes?

Q: How much does it cost to fix a foggy window in 2026?

A glass-only (IGU) swap runs $150–$400 if the frame is solid; replacing the whole window is $400–$1,100.

By Sunny Park, Founder & EditorUpdated July 12, 2026

Sunny Park founded WindowQuoteGuide and researches replacement-window pricing across U.S. markets, turning contractor quotes and public cost data into plain-English guides homeowners can actually use.

Quick answer: Fog trapped between the panes means the window's seal has failed and the insulating gas leaked out. You can't wipe it away — it's sealed inside. Fixing just the glass runs $150–$400; replacing the whole window is $400–$1,100.

Condensation sealed between two panes — the classic sign of a failed window seal.

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Foggy glass

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Seal failed

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Fix or replace

The short version: your window sprung a leak you can't see

A double-pane window is two sheets of glass with a sealed pocket of argon gas between them. That gas is the insulation. When the seal around the edge fails, the gas escapes and humid air sneaks in. The moment warm indoor air meets the cold outer pane, it condenses — and now you've got a permanent little rain cloud living inside your window.

Fog between the panes isn't dirt. It's your window quietly telling you the insulation already left the building.

Why you can't just wipe it off

People try everything — vinegar, a hairdryer, drilling a tiny hole (please don't). It never works, because the moisture is sealed inside, between two panes you can't reach. The only real fixes touch the glass itself.

What it costs in 2026

Glass-only (IGU) swap

$150–$400

Full window replace

$400–$1,100

If the frame is solid and only the sealed glass unit (the “IGU”) is fogged, a glass-only swap is the cheap, smart move. If the frame is old, drafty, or you've got fog in several windows at once, replacing the whole unit usually wins on cost-per-year.

🟢 Repair the glass if

One or two windows, frame is solid, and the rest of the window still opens and seals fine.

🔴 Replace the window if

Multiple foggy windows, the frame is 20+ years old, or you already feel drafts. Fog is often the first domino.

Does your climate make it worse?

Yes. Damp, gray places like Seattle punish window seals harder than dry ones — constant humidity plus temperature swings work the seal loose faster. Cold-snap cities like Chicago add freeze-thaw stress on top. If you live somewhere wet or freezing, foggy windows tend to show up earlier and in clusters.

Frequently asked questions

Why is my window foggy between the panes?

The sealed glass unit sprang a leak you can't see: the seal failed and moist air got inside. That's why wiping the surface never clears it.

How much does it cost to fix a foggy window in 2026?

A glass-only (IGU) swap runs $150–$400 if the frame is solid; replacing the whole window is $400–$1,100.

Does climate make foggy windows worse?

Yes. High humidity and big temperature swings stress the sealed unit faster, so failed seals show up sooner in those climates.

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Cost figures in this guide are compiled from publicly available 2026 U.S. pricing data — including ENERGY STAR, the U.S. Department of Energy, and national contractor cost guides (HomeAdvisor / Angi True Cost) — and are intended for planning only. Prices vary by region, brand, and installation method; always collect 2–3 local quotes.

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