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Siding calculator

Siding is bought in squares (100 sq ft) or by panel/carton coverage. Gables, windows, and starter strips change the count more than a flat wall photo suggests. Enter wall area (or L×H per wall), subtract large openings, add waste, read squares and optional panels from coverage you enter. This is not a color-match service and not a contractor lead form.

ft
ft
sq ft
Sum of walls
sq ft
Doors + windows
sq ft
Optional
10%
0510152025

+10% so you don't come up short

ORDER ESTIMATESIDING
Squares to order3.9
Order area390.5 sq ft
Net wall area355 sq ft
Waste10%
How it calculates
net = wall area − openings; order = net × (1 + 10%); squares = order ÷ 100; panels = ceil(order ÷ coverage) if set.

Estimate only — not a contractor bid. Confirm bag yields and local codes before you pour or order.

When to use

Re-side one elevation; estimating cartons for a garage; sanity-checking a material-only quote.

When not to

Full wrap with woven corners, fish-scale accents, and porch ceilings as one blob — split elevations. Structural sheathing / WRB rolls can be estimated as area but flashing kits are SKU-specific.

Assumptions

1 square = 100 sq ft. Waste default 10% (simple walls); 15%+ for steep gables, many windows, or diagonal patterns. Panel/carton coverage entered from the product. Openings: subtract doors/windows you measure; tiny vents often ignored in DIY waste.

Worked examples

Example 1

Two walls 40×10 and 30×10, minus 3 windows × 15 sq ft, waste 10%
→ net 700 − 45 = 655 → order ≈ 720.5 → ~7.2 squares

Order whole squares/cartons your yard sells.

Example 2

Gable end 24 ft wide × 10 ft wall + triangle, waste 15%
→ compute rectangle + triangle, then waste — gables punish tight waste %

Peak cuts generate scrap that does not reuse cleanly on the opposite rake.

How it calculates

Net wall area after openings, waste, then squares or panels.

  1. Enter wall area (or L×H) and subtract openings.
  2. Optional: panel coverage from the carton.
  3. Set waste; read squares (and panels).
net wall sq ft = Σ(wall areas) − openings
order sq ft = net × (1 + waste%)
squares = order ÷ 100; panels = ceil(order ÷ coverage_per_panel)

Common traps

  1. Exposure height (lap reveal) changes how many courses cover a wall — area still rules buying if you use square coverage.
  2. Corners, J-channel, starter are linear feet — not in the square count.
  3. Housewrap and tape are a separate roll list.
  4. Mixed elevations — north wall vs bay window: split the takeoff.

Next tool

Paint instead of re-side → paint calculator (exterior gallons).

Roof squares → roofing calculator or shingle calculator.

FAQ

Net wall area × (1 + waste%) ÷ 100 for squares, or ÷ panel coverage.

Related

Estimate only — not a contractor bid or engineered takeoff. Confirm bag yields and local codes before you pour or order.