Roof Shingle Calculator
Three bundles of asphalt shingles cover one roofing square. But a roof also needs starter strip, ridge cap, drip edge and nails — the items most homeowners forget and some quotes quietly omit. This calculator lists every quantity, with your waste factor applied.
Roof Measurements
Your Shingle Order
Everything the job needs, waste included
Mid range
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What's included
- Installation labor
- Permit
- Waste factor (%)
- Sales tax
Tax applies to materials only — labor on a real-property improvement is untaxed in most states. Check your local rate.
Warranty · Lifespan · Maintenance
Material quantities
Includes your % waste factor
| Roofing squares | |
| Shingle bundles | |
| Underlayment rolls | |
| Roofing nails | |
| Ridge cap | |
| Drip edge |
Project timeline
Typical for squares
Estimate confidence
Confidence reflects what we actually know about your inputs — whether you measured or estimated, how complex your roof is, and whether we hold labor data for your state. It is not a fabricated percentage.Sources: BLS state wage data · tracked material pricing · your measurements · Methodology
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Estimates are planning ranges, not quotes. Read our methodology.
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How we calculated your estimate
We convert your footprint and pitch into roof area, divide into squares, then multiply out every material a shingle roof needs: bundles at three per square, underlayment rolls at four squares each, nails at roughly 2.5 lb per square, plus ridge cap and drip edge estimated from your roof perimeter.
Labor rates derive from published BLS occupational wage data. Read the full methodology →
Quick cost summary
Bundles per square
3
Standard asphalt shingles
Coverage per bundle
~33 sq ft
One third of a square
Nails per square
~2.5 lb
4 nails per shingle, 6 in high wind
Underlayment
1 roll / 4 sq
Synthetic, standard width
Factors that affect the cost
Roof area
Everything scales from this. Get the area right and the rest follows.
Waste factor
Cuts, starters and ridge caps consume 10–18% of what you order.
Ridge & hip length
Ridge cap is sold by the linear foot and is a separate product from field shingles — it is often forgotten.
Ways to save money
Keep one spare bundle
Shingle colours get discontinued and dye lots vary between production runs. A spare bundle now saves a mismatched patch in five years.
Common mistakes to avoid
Forgetting starter strip and ridge cap
These are separate products from field shingles. Using cut-up field shingles as starter is a common shortcut that voids some warranties.
Under-ordering nails
Four nails per shingle is standard; six in high-wind zones. Under-nailing is the leading cause of shingle blow-off, and it voids the warranty.
Frequently asked questions
Three bundles per roofing square, plus 10–15% waste. A 20-square roof needs roughly 66–69 bundles.
About 33 square feet — one third of a roofing square.
About 2.5 pounds per square, based on four nails per shingle. High-wind zones require six nails per shingle, which increases the quantity.
Starter strip is a purpose-made product for the first course at the eaves. It has adhesive in the right place; cut-up field shingles do not. Skipping it is a common shortcut that can void your warranty.
Ridge cap shingles cover the peak where two roof planes meet. They are a separate product sold by the linear foot, and they are frequently missing from quotes.
Roughly one standard roll per four squares, though this varies by product width. Synthetic underlayment has largely replaced felt.
Yes — a spare bundle is cheap insurance. Colours are discontinued and dye lots vary, so a repair in five years may not match your roof.
Slightly. Architectural shingles are heavier and some premium lines run four bundles per square rather than three. Check the wrapper before ordering.
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