Accuracy report: one job, seven calculators
Online window cost calculators often disagree by thousands of dollars for the same house. To show where our numbers sit, we ran one identical job through six public calculators and our own, and recorded every result.
The test job
10 double-hung vinyl windows, standard size, insert (retrofit) installation, mid-range quality, in Dallas, Texas (ZIP 75201). Every calculator was run on November 14, 2026.
Results
| Calculator | 10 windows | Per window | What it assumes |
|---|---|---|---|
| Homewyse | $5,437 – $8,295 | $544 – $830 | Local ZIP labor, standard vinyl window, independent installer |
| EstimationPro | $3,825 – $9,450 | $383 – $945 | Texas priced 10% below national; includes trim and disposal |
| Window Replacement Cost Estimator | $7,975 | about $798 | Mid-range brand, retrofit, national average |
| GetWindowCost (buy + installer) | $7,465 – $9,152 | $747 – $915 | Dallas metro, Pella published rates, 10% volume discount |
| GetWindowCost (full-service company) | $11,000 – $22,000+ | $1,100 – $2,200+ | Large companies that sell and install |
| BuildMetricLab | $11,000 ($12,100 with 10% contingency) | $1,100 | One national rate, no location input |
| WindowTally (independent installer) | $5,150 – $8,120 | $520 – $810 | Dallas metro glazier wages (BLS), published window prices |
| WindowTally (full-service company) | $10,320 – $19,340 | $1,030 – $1,930 | Independent price × 1.6–3 |
For comparison, This Old House's 2026 survey of 1,000 homeowners found an average of $517 per installed window and $7,183 per project, across all window types and project sizes.
Why the results differ so much
- Who installs the windows. Buying windows and hiring an independent installer costs roughly half of what large full-service brands charge. Calculators that don't say which one they mean can look "wrong" by 100%.
- Location. Some calculators use one national price. Installer wages vary a lot: BLS puts the median glazier wage at $51.74 an hour in the Boston metro area and $21.36 in the Miami metro area.
- What's included. Trim, disposal, permits and a contingency allowance can add 10–30%.
Where WindowTally lands
Our independent-installer range for this job ($520–$810per window) overlaps Homewyse, EstimationPro, Window Replacement Cost Estimator and GetWindowCost's buy-and-install figure. Our full-service range sits inside GetWindowCost's full-service range. We show both, labeled, so you can compare a quote with the right number.
We'll re-run this test every quarter and add more cities. See exactly how our numbers are built on the methodology page.