How to measure your walls
For a simple rectangular house, measure the length and width at ground level. For an L-shaped or irregular house, walk around it with a tape and add up every wall segment, then switch to “Total wall perimeter”. Bump-outs and bay walls count; a garage counts if it gets the same siding.
Measure wall height from the bottom edge of the existing siding (usually just above the foundation) to the underside of the eave. Around 9 ft per story is common, but split-levels and raised foundations vary, so measure rather than guess.
Gable ends are the triangles of wall under each roof peak. Enter the base width and the rise from the top of the wall to the peak. If you know the roof pitch, the rise is half the gable width × pitch ÷ 12; a 30 ft gable at 6/12 rises 15 × 6 ÷ 12 = 7.5 ft. Hip roofs have no gable ends, so enter 0.
Then count windows and doors. The calculator deducts 15 sq ft per window and 20 sq ft per door, standard estimating allowances for typical openings. A two-car garage door is roughly 112 sq ft (16 × 7 ft), so count it as about five or six doors, or subtract it from your perimeter instead.
Worked example: a one-story 50 × 30 ft house
These are the calculator’s default inputs: 50 × 30 ft, 9 ft walls, one story, two 30 ft gables rising 7.5 ft, 12 windows, 2 doors, vinyl siding, 10% waste, national average prices.
| Step | Calculation | Result |
|---|---|---|
| Perimeter | 2 × (50 + 30) | 160 ft |
| Walls | 160 × 9 × 1 | 1,440 sq ft |
| Gable ends | 2 × ½ × 30 × 7.5 | 225 sq ft |
| Openings | 12 × 15 + 2 × 20 | −220 sq ft |
| Net wall area | 1,440 + 225 − 220 | 1,445 sq ft |
| Siding to order | 1,445 × 1.10 ÷ 100 | 15.9 squares |
| Installed, vinyl | 1,445 × $4–$12 | $5,780 – $17,340 |
The same walls in fiber cement come to $8,670–$21,675, engineered wood $10,115–$17,340, and wood $7,225–$21,675.
Why the cost uses net area but the order adds waste
Contractors usually quote siding per square foot of wall covered, and that price already absorbs their offcuts. So the installed estimate uses the net wall area. The waste percentage only affects the squares to order, which is the number to check if you are buying material yourself or comparing a materials list on a bid. Houses with many corners, gables, dormers or short wall runs between windows waste more; 15% is a sensible allowance for those.
What drives the price within each range
The ranges are wide because the material name covers a lot of products:
- Product grade. Thin builder-grade vinyl sits at the bottom of its $4–$12 range; thicker, insulated vinyl at the top. Fiber cement varies with factory-applied finish versus field painting.
- Removal. Tearing off old siding, especially if it’s asbestos-cement or nailed over another layer, adds labor and disposal.
- Height and access. Two- and three-story walls need scaffolding or lifts. Steep yards, landscaping right up against the walls and close neighbors slow the crew.
- Trim and details. Corner posts, window and door trim, soffit and fascia, and J-channel are often priced separately. A house with many openings has more trim per square foot.
- Sheathing repairs. Once the old siding is off, any rotten sheathing or missing house wrap has to be fixed before new siding goes on.
DIY or hire a pro?
Vinyl is the most DIY-friendly siding: it’s light and cuts with snips or a fine-tooth saw, and it hangs loosely on nails so it can expand. Getting it straight and watertight around windows still takes practice. Fiber cement is heavy, needs special blades and dust control, and manufacturers’ warranties typically depend on following their installation instructions exactly. Most homeowners hire out anything above the first story.
Related projects
Siding is often done alongside new windows, since full-frame window replacement is easiest while the walls are open; see the window replacement cost calculator. If you’re replacing the roof too, the roof replacement cost calculator uses the same footprint measurements. For wood or fiber cement that will be painted on site, estimate coatings with the paint calculator.
How this calculator works
- Perimeter = 2 × (length + width), or the perimeter you enter.
- Wall area = perimeter × wall height × stories, plus gable ends (½ × width × rise each), minus window and door deductions.
- Siding squares = net wall area × (1 + waste%) ÷ 100.
- Installed cost = net wall area × installed range per sq ft × local cost factor.
Assumptions and limitations
- Openings are deducted at standard estimating allowances: 15 sq ft per window and 20 sq ft per door.
- Gable ends are treated as triangles: ½ × base × rise.
- Installed prices are national 2026 contractor ranges per square foot of wall, applied to the net wall area. The waste allowance is used for the material order (squares), since installed per-sq-ft prices already include the installer’s offcuts.
- Excluded: removal of old siding, sheathing or house-wrap repairs, trim and soffit/fascia work, painting, and permits.
These results are planning estimates, not quotes. Local prices, site conditions and building codes vary, so get written estimates from licensed contractors before you commit to a budget.
Try your own numbers. Every price and assumption above is editable in the estimator.
Back to the siding estimatorFrequently asked questions
How many square feet are in a square of siding?
Should I subtract windows and doors?
Which siding material lasts longest?
Sources and data
- HomeGuide (2026) — siding cost
- HomeGuide (2026) — fiber cement siding cost
- HomeGuide (2026) — wood siding cost to install or replace
Prices are US national ranges reviewed October 2026 (data version 2026.10). A few values are editorial estimates where no single published source exists; the Cost Index marks each one. Read our methodology and editorial policy.