Subtract windows and doors for a tighter material count.
MEASURE. ESTIMATE. BUILD.
Siding Calculator
Enter your wall dimensions to estimate siding in squares (100 ft²) and panels, with a waste allowance for cuts and trim.
01 / PROJECT DIMENSIONS↙
Total wall length
Wall height
Waste %%
Change any measurement to update your estimate.
02 / YOUR MATERIAL ESTIMATE
You need approximately
4 squares
covers 352 ft² (incl. waste)
- Area to cover
- 352 ft²
- Exact amount
- 3.52 squares
Field notes
Waste climbs with corners, not square footage. A plain gable end runs 10%; a house with dormers, bays, and multiple gables can waste 15% because every angled cut leaves an unusable offcut. Measure each wall separately and subtract only the big openings — trying to net out every window invites a shortfall. Buy one extra square and keep it for storm repairs; dye lots shift between orders.
How the siding calculator works
The math behind the tool:
wall area ft² = Σ(wall height × wall length) − openings
squares = wall area ÷ 100 × (1 + waste%)Sources: Polymeric Exteriors Alliance (formerly Vinyl Siding Institute) (siding coverage and installation standards).
Frequently asked questions
How many squares of siding do I need?
Divide your total wall area (in ft²) by 100 to get siding squares, then add 10% for waste. A 1,500 ft² wall area needs about 16.5 squares of siding.
How much waste should I add for siding?
Add about 10% for straight walls and 15% for homes with many corners, gables, or dormers, since angled cuts create more offcuts.
How do you calculate siding square footage?
Multiply each wall run by its height and add them up. For a gable end, take the width times the height to the peak and halve it — a gable is a triangle. Then add 10% for waste, and more on a house with many windows, corners or dormers.
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