Siding Squares Calculator
Convert an area in square feet into whole squares of siding — the trade unit — with a waste factor. One square = 100 sq ft.
1,336 sq ft plus 10% waste is about 15 squares. Siding is sold and quoted by the “square” — 100 square feet; divide your area by 100, add a waste factor for cuts and trim, and round up.
1 Enter your numbers
Siding is counted in squares. One square is 100 square feet of finished wall — a unit borrowed from roofing that keeps big numbers manageable and matches how suppliers and contractors talk. A quote of “$700 a square” or “15 squares to do the house” only makes sense once you can move between square feet and squares fluently.
This tool does that conversion, adds a waste factor for cuts, and rounds up to whole squares — because you order and price in whole units. Set the waste factor to zero if you just want the bare square count for a known area.
Why round up
Fractional squares do not exist as an order. 14.7 squares is 15 squares on the truck, and the last fraction is where the corner cuts and the final short course come from. Rounding up is a hard requirement of buying whole boxes and bundles, not a safety margin on top of the waste factor — the waste factor handles the offcuts; the ceiling handles the packaging.
Formula
squares = ⌈ area × (1 + waste%) ÷ 100 ⌉
1 square = 100 sq ft. The ⌈ ⌉ brackets round up to the next whole square. With waste at 0, this is simply the area divided by 100, rounded up.
Worked example
For 1,336 sq ft of net siding area:
- No waste: 1,336 ÷ 100 = 13.36 → ⌈13.36⌉ = 14 squares
- With 10% waste: 1,336 × 1.10 = 1,469.6 → ÷ 100 = 14.70 → ⌈14.70⌉ = 15 squares
So the sample house is 14 bare squares of wall, 15 squares once you allow for waste — the number to order and to price against.
Squares in practice
- Order in whole squares. Suppliers sell whole boxes and bundles; the rounded-up square count is your order, not your exact usage.
- Waste is separate from rounding. The waste factor covers cuts and damage; rounding up covers packaging. You need both.
- Match the waste to the layout. 10% for a plain rectangle, 12–15% for a complex house, more for shakes and diagonals.
- Squares are not boxes. One box of vinyl covers ~2 squares; a bundle of cedar shingle covers a fraction of a square. Convert with the boxes by material calculator.
Reference table
Labeled planning snapshot — measure your actual layout. Waste covers cuts, corners, gables and mistakes.
| House layout | Waste factor |
|---|---|
| Simple rectangle, few openings | ~10% |
| Average house, some gables & corners | 10–12% |
| Complex — many corners, gables, dormers | 12–15% |
| Cedar shakes / shingles / diagonal pattern | 15%+ |