Fiberglass windows are a popular choice because of their very strong and stable. Here’s what they cost, how long they last, and how they compare.
Cost at a glance
| Cost | Source | |
|---|---|---|
| National average (installed) | $564 | This Old House, window replacement cost survey (2026) |
| Typical range, standard sizes | $500-$1,500 | TheWindowCo estimate from published averages |
| Pella fiberglass & wood lines | $1,100-$2,200+ | Pella.com cost guidance |
| Typical lifespan | 40+ years | TheWindowCo estimate from published averages |
What affects the price
- Pros: Very strong and stable, paintable, slim frames.
- Cons: Costs more than vinyl, fewer installers.
- Size and style matter as much as material: a large casement in vinyl can cost more than a small double-hung in fiberglass.
- Glass package: low-E coatings and argon gas are standard on most mid-range lines; triple-pane costs extra.
Ways to save
- Compare the same style and size across two materials before deciding.
- Ask whether the quote is for an insert or full-frame installation.
- Look for ENERGY STAR certification for your climate zone if you want utility rebates.
Get an accurate price
Online averages are a starting point. Window prices depend on exact sizes, your home’s condition and local labor rates, so the only reliable number is an itemized, in-home quote. Compare at least three, and use our window cost calculator to sanity-check them.
Frequently asked questions
How long do fiberglass windows last?
Typically 40+ years, depending on climate, installation quality and maintenance.
Are fiberglass windows worth the cost?
Compare total cost over the years you’ll stay in the home: cheaper frames that need replacing sooner can cost more in the long run.
What readers paid
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Questions from readers
Question about Fiberglass windows? Ask it here. We answer the useful ones on this page, in general terms.
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