How this shingle calculator works
Shingles are sold in bundles, three to the square (100 ft² of roof). The calculator gets your true roof area from the ground: footprint × the pitch multiplier, then waste, then whole bundles:
bundles = squares × (1 + waste%) × 3, rounded up
Worked example: shingles for a 40 × 30 footprint
1,200 ft² of footprint at 6:12 is 1,200 × 1.118 = 1,342 ft² of actual roof — 13.4 squares. Add 10% waste and multiply by three: 45 bundles, about $1,890 at $42 a bundle, plus 2 rolls of synthetic underlayment at 10 squares a roll.
How many bundles of shingles by roof size?
| Footprint | 4:12 | 6:12 | 8:12 |
|---|---|---|---|
| 30 × 25 (750 sf) | 27 | 28 | 30 |
| 40 × 30 (1,200 sf) | 42 | 45 | 48 |
| 50 × 30 (1,500 sf) | 53 | 56 | 60 |
| 60 × 35 (2,100 sf) | 74 | 78 | 84 |
How to measure a roof for shingles
- From the ground: footprint including overhangs × pitch multiplier — the method this calculator automates. Get the pitch with the roof pitch calculator.
- Waste honestly: 10% on straight gables; 15% with hips, valleys or dormers — valley cuts eat shingles.
- Don't forget the extras: starter along eaves and rakes, cap shingles on ridges and hips, ice barrier where code requires it, and drip edge all around.
Shingle FAQ
How many bundles of shingles are in a square?
Three bundles cover one square — 100 ft² of roof — for standard architectural shingles, each bundle covering about 33 ft². Some heavyweight and designer lines run 4–5 bundles per square; the wrapper states the coverage.
How many shingles do I need for a 1,200 sq ft roof footprint?
At a 6:12 pitch the true roof area is 1,200 × 1.118 = about 1,342 ft² — 13.4 squares. With 10% waste that is 45 bundles, plus 2 rolls of synthetic underlayment. The calculator recomputes for your pitch and waste.
How much does a square of shingles cost in 2026?
Architectural shingles run roughly $120–150 per square in materials ($40–50 a bundle), before underlayment, starter, caps, nails and disposal. Installed, most markets see $450–700 per square depending on pitch and tear-off.
How do I measure my roof for shingles from the ground?
Measure the building footprint including overhangs, multiply by the pitch multiplier (1.118 for 6:12 — the pitch calculator gives you the number), and you have roof area without leaving the ground. Complex hip-and-valley roofs deserve a plane-by-plane takeoff and 15% waste.
How many nails per square of shingles?
Four nails per shingle standard — about 320 nails per square — and six per shingle (≈480) in high-wind zones or where the manufacturer requires it. That is roughly 2½ lb of coil nails per square at four-per.
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