A typical whole-house window replacement in St. Louis runs about $7,000 to $26,000 installed in 2026, and a single opening about $550 to $2,800, with the spread explained by four things: how many windows, what frame material, whether the old frame stays (insert) or goes (full-frame), and whether the wall is siding over frame or brick. Two more things move a St. Louis price that national guides never mention: a historic-district product requirement, and lead-safe work on a pre-1978 house. Every one of those is a line on our quote.
What does one window cost installed?
| Style and material | Insert, frame wall | Full-frame, frame wall | Insert, brick | Full-frame, brick |
|---|---|---|---|---|
| Vinyl double-hung or slider | $550 – $950 | $800 – $1,300 | $700 – $1,200 | $1,000 – $1,700 |
| Vinyl casement or awning | $650 – $1,100 | $900 – $1,500 | $800 – $1,400 | $1,150 – $1,950 |
| Casement, full-frame, steel or aluminum sash removed (1950s–70s), vinyl to fiberglass | — | $900 – $1,900 | — | — |
| Fiberglass double-hung | $850 – $1,350 | $1,050 – $1,650 | $950 – $1,500 | $1,100 – $1,900 |
| Composite double-hung | $900 – $1,450 | $1,100 – $1,750 | $1,000 – $1,600 | $1,200 – $2,000 |
| Aluminum-clad wood double-hung | $1,100 – $1,800 | $1,350 – $2,200 | $1,250 – $2,000 | $1,500 – $2,600 |
| Historic replica (CRO-approved wood, clad, composite or finished aluminum) | sash kit $1,100 – $1,900 | — | — | $1,500 – $2,800 |
| Picture / fixed, vinyl | $500 – $900 | $750 – $1,250 | $650 – $1,100 | $950 – $1,600 |
| Bay or bow (3-lite), vinyl | — | $2,800 – $5,500 | — | $3,200 – $6,500 |
| Basement hopper, vinyl | $350 – $650 | $500 – $900 | $450 – $800 | $650 – $1,100 |
| Egress window into existing basement opening | — | $1,200 – $2,200 | — | $1,400 – $2,600 |
Planning bands for the St. Louis metro, 2026, standard sizes, double-pane low-e argon glass. Triple-pane adds roughly $120–$250 per opening. Oversized units, custom shapes and arched heads are quoted after measure.
What does a whole house cost?
| House | Openings | Typical installed |
|---|---|---|
| 1995 St. Charles County two-story, vinyl inserts | 14 | $7,000 – $12,100 |
| 1962 Florissant brick-veneer ranch, steel casements out, full-frame vinyl casements | 10 | $9,100 – $15,300 |
| 1925 University City brick bungalow, composite, inserts to full-frame | 12 | $11,500 – $23,400 |
| 1905 Soulard brick flat, CRO replica on the street side (4), composite full-frame on the alley side (8) | 12 | $14,800 – $26,300 |
| 1988 St. Peters two-story, fiberglass inserts | 18 | $13,600 – $21,600 |
Whole-house figures are the instant estimate's output for those inputs (model v0.1), including the quantity curve and lead-safe adder where the era applies.
How do these compare with the numbers you will find elsewhere?
The most-cited aggregator figure for St. Louis is Angi's: an average of about $6,278 per project with a typical range of $3,108 to $9,479, and $300 to $1,500 per window (Angi, St. Louis page, read October 13, 2026). EcoWatch's St. Louis page puts a typical single window at about $600 installed and reports customer-submitted figures of $750–$1,250 per window for one national brand and $300–$525 for another.
Those figures are not wrong; they are averages over everything — unit-only purchases, partial jobs, three-window jobs, vinyl inserts in frame walls alongside clad-wood full-frame in brick. Our bands are higher at the top because they include the kinds of work St. Louis has a lot of and the aggregators average away: masonry openings, historic product, and lead-safe setup. As of this update no St. Louis installer other than this one publishes a price; every company we checked requires an in-home appointment to give one.
What moves a St. Louis price?
- Count. Setup, lead-safe containment and travel are spread across the openings; per-window cost falls as the count rises. Three windows cost more each than fourteen.
- Frame material. Vinyl is the floor; fiberglass and composite are roughly 30–50% more; clad wood roughly double; historic replica double to triple.
- Insert or full-frame. Full-frame runs about 25–60% more per opening. In St. Louis it is needed more often than elsewhere: steel and aluminum sash in the 1950s–60s belt, rot and settlement in pre-war frames. See insert vs. full-frame.
- The wall. A brick masonry opening adds roughly $150–$400 per opening over a frame wall for anchoring, flashing and trim work in view. See the brick guide.
- Historic district. If the house is in one of the City's eighteen districts, street-facing windows must come from the CRO approved list — wood, clad, composite or finished aluminum, no vinyl — which sets the product class. See the district rules.
- Lead-safe work. On a pre-1978 house — 86% of the City, 69% of the County — window replacement always falls under the EPA's RRP rule; containment, HEPA cleanup and verification add roughly $40–$120 per opening depending on method. See lead-safe replacement.
- Glass package. Low-e argon is in the base price. Triple-pane, laminated (noise or security) and tempered (where code requires it near doors, tubs and floors) are adders.
- Condition. Lintel repair, sill replacement, rotted framing behind the window and plaster repair are quoted separately when the measure finds them — never as a surprise on install day.
How does "buy two, get two free" math work?
A discount is only a discount against a real price, and in this market the real price is rarely published. Promotions published by St. Louis window companies in October 2026 included "Buy 4 Windows, Get 4 FREE," "Buy 2 Windows, Get 2 FREE" with "40% off windows," and "Save 30-50%," all tied to an in-home appointment and in one case "valid only at the initial in-home estimate." The arithmetic to do is simple: divide the final written number by the number of openings and compare the per-opening figure, same material and method, against the table above and against the other quotes. The headline percentage is irrelevant; the per-opening installed number is the price.
Financing is part of the price too. Published terms in the St. Louis market in October 2026 ranged from 6.99% for 60 months at one company to deferred-interest plans at 17.99%, 28.99% and 29.49% APR at others. A "no payments for a year" plan at 29% is expensive money if the balance is not cleared on time. Comparing window quotes goes through this line by line and includes a worksheet.
Is sales tax on the quote?
In Missouri, a contractor improving real property is treated as the final consumer of the materials and pays sales tax when buying them (12 CSR 10-112.010; confirmed again in a 2025 Department of Revenue letter ruling). The materials tax is already inside the material cost. If a quote adds a sales-tax percentage on top of the whole installed price, or a tax line on labor, ask what it is for.
What about the tax credit?
There is no federal credit for windows installed in 2026. The Section 25C credit (up to $600 on ENERGY STAR Most Efficient windows) ended for property placed in service after December 31, 2025. Ameren Missouri, Ameren Illinois and Spire do not rebate windows. Residential PACE through the Missouri Clean Energy District is suspended. Do not let a credit that no longer exists carry a quote; see tax credits and rebates in 2026.
What does repair cost instead?
A fogged insulated glass unit replaced in the existing sash runs about $220–$550; a sash cord $110–$220; new balances $90–$200; a painted-shut sash freed and weatherstripped $150–$350. In a pre-war house with original wood sash, restoration is often the better buy and, in a historic district, the preferred one. See window repair.
Frequently asked questions
Why is your range wider than Angi's? Because it includes brick full-frame work and historic product, which the aggregator average dilutes. Our low end is close to theirs; our high end is the City's housing stock.
Can I see a number for my house without an appointment? Yes — the instant estimate takes count, style, material, method, wall and era and gives a range with no contact details.
Are these prices per window or per project? Per opening, installed, in the first table; per project in the second.
Does the price change in winter? Lead times are shorter and schedules looser, so winter quotes are often keener. The install itself is the same.
Do you charge for the measure visit? No.
Next step
Window replacement is the service for most houses. Or go straight to the instant estimate. Related: insert vs. full-frame · comparing quotes.