Estimate your 2026 Seattle window replacement — vinyl, fiberglass and wood-clad frames; double-hung, single-hung, slider, casement, awning, picture, bay and bow. Enter each window's type, size and quantity, then add old-window removal, interior trim and the energy-efficient option. The calculator returns an itemized per-window price and a job total.
This is the tool version of our Seattle Window Replacement Costs 2026 & Rebates Guide guide, which walks through utility rebates, the HOMES program eligibility math, and per-window material tier tradeoffs. Read the guide for the rebate strategy; use the calculator below for your project number.
Select additional services. Each window's type sets its material and line.
High-performance windows with improved insulation
Professional interior trim installation
Professional removal and disposal of existing windows
Your Estimate
Configure your windows and click "Calculate Estimate"
No estimate yet
Add windows and calculate
Compare Window Materials
You pick the material in each window's Window Type above: vinyl windows are the Standard line, and fiberglass and wood-clad windows are the Premium line.
🪟
Vinyl
Durability
Good
Maintenance
Low
✨
Fiberglass
RECOMMENDED
Durability
Excellent
Maintenance
Very Low
🪵
Wood Clad
Durability
Good
Maintenance
Moderate to High
← Swipe to compare →
How Our Window Replacement Cost Calculator Works
Professional window replacement estimates for Seattle-area homes
Accurate Cost Estimation
Our window replacement calculator prices each window from Kolmo's own window catalog and per-window installation rates. For each
group of windows you choose a window type from the catalog, which sets both the style and the frame (a double-hung vinyl or a wood-clad
casement, for example), and enter the width and height in inches and the quantity. Windows are priced by size in united inches, width plus
height, so a larger opening costs more. For the whole job you choose whether to add interior trim work, remove the old windows, and
upgrade to the energy-efficient option. Installation is billed per window, not by the hour: a standard install is $160 a window, any window
whose width plus height is more than 120 inches is billed at the full-frame rate of $350, and bay and bow windows are billed at the custom
rate. Hardware, sealant and accessories are 5% of the window cost.
What The Calculator Includes
Every window replacement estimate is itemized: the window units at the type and size you chose, a hardware, sealant and accessories
line, and installation per window. Turn on removal and the old windows are taken out at $50 a window. Turn on trim work and the calculator
adds casing by the linear foot, figured from each window's size, plus trim installation by the linear foot; on ten 36 x 48 inch windows
that is 140 feet of MDF casing for $252 and $1,400 of trim installation. The energy-efficient option adds 15% to the window price, $59.50
a window on a 36 x 48 inch double-hung vinyl once the hardware allowance is included. There is no permit line and no contingency line.
Lead-safe work practices on a home built before 1978, repairs to rotted rough openings, and utility rebate eligibility are not part of the
calculator; we handle them at the walkthrough.
Seattle-Specific Considerations
Seattle's climate makes installation quality as important as the window itself. The Pacific Northwest's high rainfall and humidity
punish improper flashing and sealing, which lead to the rot and mold problems that plague many Seattle homes. Many Seattle homes built
before 1990 have original single-pane windows or early double-pane units that are now failing, with rot around frames from decades of
moisture exposure. When the frame around an old window has rotted, the fix is often a full-frame replacement down to the rough opening,
and the extent of the damage only shows once the old unit comes out, so it is assessed on site rather than priced in advance. Seattle's
seismic zone calls for proper fastening and flexible sealing methods. The calculator's energy-efficient option shows what a
higher-performance unit adds to the price; whether an upgrade qualifies for a Seattle City Light or PSE rebate is something we check with you
before you commit. Washington requires window contractors to be registered with L&I, bonded and insured, and proper L&I coverage protects
you from liability if installers are injured on your property.
Using The Calculator Effectively
For accurate estimates, count all windows needing replacement and measure each opening carefully, width and height in inches. Group
identical windows into one row with a quantity. Choose each window's type from the list; the type sets the style and the frame, and the
price follows the size, so a wood-clad casement costs more than a double-hung vinyl window of the same size ($756 against $378 at 36 x 48
inches). Enter large windows at their real size: once width plus height passes 120 inches, installation moves to the full-frame rate.
Choose a bay or bow type for those units so they are priced at the custom rate. Turn on removal if old windows are coming out, trim work if
you want new interior casing, and the energy-efficient option to see what it adds. The estimate lists each window group and each
installation line with a time estimate in working days, and you can change any input to compare options.
Window Replacement Cost Calculator: common questions
How long do replacement windows last in Seattle?
Quality vinyl or fiberglass windows properly installed typically last 20-30 years in Seattle's climate. Wood windows require more maintenance but can last 30+ years with proper care. Aluminum-clad wood combines durability with beauty for 25-35 year lifespans. The key factor is proper installation with adequate flashing and sealing - poorly installed windows fail prematurely due to water infiltration causing frame rot and seal failure.
Do I need triple-pane windows in Seattle?
The calculator does not price triple-pane glass; it has no glazing input. Its energy-efficient option adds 15% to the window price, which on a 36 x 48 inch double-hung vinyl window is $59.50 a window with the hardware allowance. Whether triple glazing is worth it depends on the specific product, the house and how long you plan to stay, so if you are considering it, ask us to price it against a double-pane unit at the walkthrough.
Should I replace all windows at once or in phases?
The calculator prices every window at the same per-window rates, so it shows no discount for doing them together: ten 36 x 48 inch double-hung vinyl windows with removal come to $6,069, about $607 a window, and a single one comes to $607. A single mobilization can still simplify a project, and we can look at that at the walkthrough. If budget means phasing, prioritize windows with visible problems like condensation between panes, rot or difficult operation, then the rooms you use most. Many homeowners replace windows over 2-3 years, prioritizing by urgency and budget availability.
Why trust this window replacement estimate?
Kolmo LLC, established 2025, is a licensed, bonded and insured Washington general contractor (License #KOLMOL*753JS) working across Seattle and King County. This window replacement calculator prices from Kolmo's own material catalog and labor rates, not national averages. Every estimate returns an itemized breakdown of materials and labor, and the line items reconcile to the total so you can check the arithmetic yourself, and the cost of every option you switch on appears as its own line. Treat the result as a planning estimate rather than a quote: the final price is set after a walkthrough of the actual conditions, which is free and carries no obligation.
What this calculator captures
Installed prices from this calculator for 2026, for 36×48 in vinyl windows with the old window removed. Ten vinyl double-hung windows come to $6,069. Fiberglass, wood-clad, bay and bow windows are priced in the calculator above.
Vinyl double-hung
$607
One 36×48 in window, old window removed. A single-window job is the same price.
Ten vinyl double-hung
$6,069
Ten 36×48 in windows, old windows removed.
Vinyl single-hung
$563
Per 36×48 in window in a ten-window job, old windows removed: $5,628 for ten.
Using this calculator
Does this estimate check HOMES or utility rebates?
No. The calculator prices the windows and the install; it does not check rebate eligibility. Ask us and we'll look at the HOMES program and utility rebates for your project before you commit.
Does the calculator include lead-safe work rules for pre-1978 homes?
No. Lead-safe work practices (EPA RRP) on a pre-1978 home are priced on site, not in the calculator.
What kind of install does the calculator price?
A standard replacement install for each window, and a full-frame install for any window whose width plus height is more than 120 inches. Bay and bow windows are priced at the custom install rate. There is no per-window retrofit option in the calculator.
Are grilles, storm-shutter, or specialty shapes priced in?
Bay and bow windows are. Grilles, half-rounds, trapezoids and storm-shutter hardware are not in the calculator; request a custom quote if you need them.
How does order lead time affect Seattle projects?
Stock vinyl windows ship in 2-4 weeks from Seattle-area suppliers. Wood-clad and custom sizes run 8-14 weeks due to factory backlog. The calculator returns cost only; plan project start around material lead time. Kolmo can install in phases to accommodate staggered deliveries on larger whole-home jobs.
