How this roofing calculator works
Every line on a roofing order scales from the same number — squares of actual roof surface — so this calculator computes that once and fans it out, using the same engines as the single-purpose shingle and sheathing tools:
3 bundles · 320 nails · ⅒ roll per square · sheathing = area ÷ 32 ft²
Worked example: materials for a 40 × 30 roof at 6/12
1,342 ft² of roof is 13.42 squares — with 10% waste: 45 bundles plus 2 of ridge cap, 2 rolls of underlayment, 47 sheets of sheathing, 15 sticks of drip edge for the 147 lf perimeter, and roughly 4,700 roofing nails — ≈ $3,224 in materials at the default prices.
How much roofing material by roof size?
| Footprint | Squares | Bundles | Sheets | Materials |
|---|---|---|---|---|
| 30 × 24 ft | 8.05 | 27 | 28 | $1,985 |
| 40 × 30 ft | 13.42 | 45 | 47 | $3,224 |
| 50 × 30 ft | 16.77 | 56 | 58 | $3,930 |
| 60 × 36 ft | 24.15 | 80 | 84 | $5,615 |
Roofing FAQ
How do I calculate roofing materials?
Everything hangs off squares: footprint × pitch multiplier gives true roof area, divide by 100 for squares, then each material has a per-square factor. The default 40 × 30 ft roof at 6/12 is 13.42 squares — 45 bundles, 2 rolls of underlayment, 47 sheets of sheathing, 15 sticks of drip edge, about $3,224 in materials.
How many squares is my roof?
Roof area ÷ 100. A 1,200 ft² footprint at 6/12 is 1,342 ft² of actual surface — 13.42 squares. Steepness matters more than people expect: the same footprint at 12/12 is 17 squares.
How much roofing material do I need per square?
3 bundles of shingles, about 320 nails, one-tenth of an underlayment roll, and a bit over 3 sheets of sheathing if you are re-decking. The calculator applies the waste factor to all of them at once, which is where hand math usually slips.
How much drip edge do I need?
The full perimeter: both eaves plus all four rakes — and the rakes run the slope, so they get the pitch multiplier too. The default roof needs 147 lf, which is 15 ten-foot sticks. Eaves get drip edge under the underlayment; rakes over it.
What is in a complete roof materials list?
Shingles, ridge cap, underlayment, drip edge, nails, and sheathing if the deck is being replaced — that is this calculator. Priced separately because they are job-specific: ice-and-water barrier in cold climates, pipe boots, and any flashing at walls, chimneys and valleys.
How much does it cost to roof a house?
The default roof is about $3,224 in materials. Installed, architectural shingle roofs typically run $4.50–8 per square foot of roof area in 2026 — tear-off, steepness and access move the labor side far more than the shingle brand does.
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