So how much does double glazing cost per window in the UK? As a rough rule: £300–£600 per window for standard uPVC casements, £600–£1,200+ for sash windows or aluminium. A typical 3-bed semi with 8–10 windows usually costs £4,000–£8,000 fitted.

But per-window pricing is slippery — companies quote whole-house prices, and the range is huge. Here’s what actually drives the cost, and how to make sure you’re comparing like with like.

How Much Does Double Glazing Cost Per Window in the UK? By Type

• uPVC casement (standard): £300–£600. The workhorse — cheapest, lowest maintenance, suits most modern and 20th-century homes.
• uPVC sash (vertical sliding): £800–£1,400. Needed for period properties; the mechanism costs more.
• Aluminium casement: £600–£1,200. Slimmer frames, more glass, contemporary look. Pricier but beautiful.
• Timber: £800–£1,500+. The premium choice for listed buildings and conservation areas — and the only option where planning requires it.
• Bay window: £1,200–£2,500+ depending on sections. Bays are essentially 3–5 windows plus structural work.

These are supply-and-fit prices from reputable firms. Anyone quoting £150/window is cutting corners you’ll regret — thin frames, no reinforcement, cowboy fitting.

What Affects the Price (Beyond the Window Itself)

• Size: obvious, but big picture windows cost disproportionately more — large glass units are heavy and need stronger frames.
• Opening style: fixed panes are cheapest; tilt-and-turn and sliding mechanisms add cost.
• Glass specification: standard double glazing vs acoustic glass (for noisy roads, +20–30%) vs triple glazing (+30–50%). Low-E coating and argon fill are standard on decent units now — don’t pay extra for them as “upgrades”.
• Installation complexity: stone mullions, bay structures, high-level windows needing scaffolding — labour varies enormously.
• Location: London and the South East run 20–30% above the North.
• Quantity discount: per-window cost drops significantly on whole-house jobs vs one or two windows.

How to Get Honest Quotes

• Get 3–4 quotes — mix of national firms and local independents. Locals are often 20–30% cheaper for equal or better quality.
• Insist on itemised quotes: per-window breakdown, glass spec, frame spec, installation, scaffolding, waste removal, guarantees. Vague quotes hide vague work.
• Check FENSA or CERTASS registration — legally required for replacement windows in England and Wales. Verify on the FENSA website; it also means Building Regulations compliance is handled.
• Never sign on the day. High-pressure “today only” discounts are a red flag. A genuine quote is valid for 30+ days.
• Ask about the guarantee: 10 years is standard on frames and installation. Get it in writing — and check whether it’s insurance-backed (so it survives if the company folds).

Is It Worth It? The Honest Maths

Let’s be straight: double glazing is a slow financial payback (often 20+ years on energy savings alone — roughly £110–£150/year for a typical home per Energy Saving Trust figures). You don’t buy double glazing to save money on bills.

You buy it for: comfort (no more cold draughts by the window), noise reduction (transformative on busy roads), security (modern locking vs rattly old catches), condensation reduction, and saleability (estate agents confirm buyers expect it). If your windows are rotten, draughty or single-glazed, it’s absolutely worth doing — just do it for the right reasons.

Cheaper Alternatives Worth Considering

• Secondary glazing: £300–£600/window, fitted inside existing windows. Excellent for period properties and listed buildings where replacement isn’t allowed — and better for noise than standard double glazing.
• Draught-proofing + heavy curtains: £200–£500 total. Won’t match double glazing, but closes much of the comfort gap for a tenth of the price.
• Replace the worst offenders only: the rotten bathroom window and the rattling bedroom sash now; the rest when budget allows. No rule says it must be all at once.

Windows: Getting the Best Deal

• Buy in winter. Window companies are quietest November–February and discount aggressively. The same windows can cost 15–20% less than in the spring rush.
• Whole house beats piecemeal. Per-window costs drop 20–30% on full-house jobs vs one or two windows — the setup costs are shared.
• Local independents vs nationals. Get both quotes. Nationals charge for the brand and the salesman’s commission; local firms are often 20–30% cheaper for equal or better installation.
• Don’t pay for “upgrades” that are standard. Low-E glass, argon fill, multi-point locking — these are baseline on decent windows in 2026, not premium extras. Challenge any quote that lists them as add-ons.
• Negotiate. Window pricing has margin built in — polite negotiation (“your competitor quoted X”) routinely saves 10–15%. The first price is never the final price.
• Check the guarantee’s small print. “10-year guarantee” means nothing if the company folds. Insurance-backed guarantees cost the firm a little more and protect you completely — ask for one.

Keep in Mind

Planning permission is occasionally needed for windows — listed buildings, conservation areas, and flats (where the freeholder’s consent substitutes). Check before ordering, not after. Standard replacements in ordinary houses are covered by FENSA-registered installers without separate permission.

• Keep your FENSA certificate forever — solicitors ask for it when you sell. Lost it? FENSA can reissue for a small fee.
• Check trickle vents are included — building regulations require background ventilation in replacement windows. Vents aren’t optional extras.
• Photograph the installation — frame fixings, sealing, insulation around frames. If problems arise later, photos prove what was done.

The Short Version

Standard uPVC casements: £300–600 per window fitted; whole 3-bed house typically £4,000–8,000. Get itemised quotes from local independents and nationals, verify FENSA registration, never sign on the day, and buy for comfort and quiet — the energy payback alone is 20+ years, but the daily quality-of-life gain is immediate.

• Winter quotes are 15–20% cheaper — installers discount when quiet.
• Insurance-backed guarantees protect you if the firm folds. Ask for one.

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Quote Smart, Buy Once

Double glazing in the UK costs £300–£600 per standard uPVC window and £4,000–£8,000 for a typical whole house. Get itemised quotes from a mix of local and national firms, verify FENSA registration, never sign on the day, and buy it for comfort and noise — not just energy savings. Done right, good windows last 25+ years.