Guide
What is a roof square?
The unit explained: 100 sq ft, and how squares become bundles and dollars.
Roof square calculator
A roofing square is 100 square feet — the unit every price, every bundle count and every labour rate in this trade is quoted in. This calculator takes the footprint, corrects it for pitch, and adds the waste the roof’s shape actually earns, so the number you order against is the number you cut against.
Squares takeoff
Footprint, not roof surface — the pitch does that conversion. Pre-filled with a 48 × 34 ft ranch at 6/12.
21.0 squares
ordered · 18.2 net + 15% waste
| Takeoff line | Value |
|---|---|
| Footprint | 1,632 sq ft |
| Slope multiplier at 6/12 | × 1.118 |
| Roof surface | 1,825 sq ft |
| Net squares | 18.25 sq |
| Waste allowance | +15% |
| Order | 21.0 sq |
Why the footprint is never the answer
Plan area is what the house covers on the ground. Roof area is what the shingles cover on the slope, and the two differ by the pitch multiplier — 5.4% at 4/12, 11.8% at 6/12, 41.4% at 12/12. Order against the footprint on a steep roof and you are short by more than a whole day of material. The pitch calculator derives the multiplier from rise over run.
What waste actually pays for
Waste is not spoilage. It is the starter course cut from full shingles, the hip and ridge caps cut from field shingles, the valley cuts, the offcuts at rakes and around penetrations, and the two or three bundles you leave in the garage for the next storm. A plain gable earns 10%. Hips and valleys earn 15% because every course meeting a valley loses its tail. A cut-up roof with dormers earns 18% and sometimes more.
Round up, never down
Shingles come in bundles, not fractions of a square. Round the ordered figure up to the next whole bundle on the bundle calculator. A short load stops a crew for half a day; three spare bundles cost less than that half-day.
A worked takeoff
A 48 × 34 ft ranch is 1,632 sq ft of footprint. At 6/12 the multiplier is 1.118, so the roof surface is 1,825 sq ft — 18.25 squares. Hips at both ends and a valley over the entry put it in the moderate band, so 15% waste takes the order to 21.0 squares, which is 63 bundles of standard three-bundle-per-square shingles. Price that at installed cost and you have a bid.
Related
Tool
Shingle bundle calculator
Squares to bundles, starter, ridge cap and nails.
Tool
Roof area calculator
Gable, hip and shed shapes worked separately and added.
Sources
- Fixr, Roof Replacement Cost (updated 4 February 2026) — read 2026-09-04