Siding Calculator
Estimate siding squares needed for exterior walls, minus doors and windows.
Siding squares needed
9 squares
- Net wall area
- 768 sq ft
- Area with 10% waste
- 844.8 sq ft
How we calculate this
Net wall area = (perimeter × wall height) − (doors × 21 sq ft) − (windows × 15 sq ft). Siding is sold in "squares" of 100 sq ft, so squares needed = waste-adjusted net area ÷ 100, rounded up.
Example
Measuring tips
Measure the full perimeter of the exterior walls being sided, then multiply by wall height for gross area. Count every door and window to subtract — most contractors use standard averages (21 sq ft per door, 15 sq ft per window) unless exact sizes are known.
Common mistakes
- Forgetting gable ends, which add significant area on homes with pitched roofs.
- Not adding enough waste allowance for corners, starter strips and J-channel trim cuts.
- Mixing siding profiles or lot numbers, which can cause visible color variation.
Frequently asked questions
How many squares of siding do I need for a 2,000 sq ft house?
It depends on wall height and openings, not floor area — measure the actual exterior wall perimeter and height, then subtract doors and windows using this calculator.
What is a "square" of siding?
A square is 100 square feet — the standard unit siding is bought and sold in.
Related calculators
Estimates are provided for planning purposes. Actual material requirements may vary based on supplier specifications, compaction, site conditions, installation method, waste, and local code.