Roof Shingle Calculator — Roof Planes, Bundles & Cost
Plan shingle bundles for multiple roof planes, with pitch, product coverage, starter strips, ridge caps and your material quotes.
45 bundles of shingles for the example roof
A 40 × 30 ft horizontal roof projection at 6:12 pitch, 10% waste and 3 bundles per roofing square. Replace these example measurements with your own.
1. Measure your roof planes
Enter each plane once. Surface dimensions are measured on the slope. A horizontal projection needs its own pitch; include overhangs in the dimensions. Use drawings or an existing measurement report rather than climbing onto the roof.
Triangle and trapezoid height is perpendicular to the base, in the same measurement plane. Sketches show the entered shapes separately; they are not an assembled roof or a cutting plan.
2. Choose bundle coverage
Copy coverage from the wrapper or supplier specification. “3 bundles per square” means 3 bundles cover 100 ft²; a rounded 33.3 ft² figure is not exactly equivalent. Waste is your allowance, not an optimized cutting estimate.
3. Starter strips and ridge / hip caps
Measure these separately. Starter length commonly includes eaves and rakes; ridge-cap length includes the ridges and hips to cover. Confirm the product instructions. Leave out accessories you do not want estimated.
Quote currency
Prices are optional. Leave unknown quotes blank; enter 0 only for a free item. The subtotal includes entered material quotes only, excluding labor, tax, removal and delivery.
Your material order
Whole packages to buy
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How roof shingles are calculated
For a rectangle, multiply width by perpendicular height. A triangle uses half that area. For a trapezoid, multiply the average of its two parallel edges by the perpendicular height. If these are horizontal projections, multiply by √(1 + (pitch ÷ 12)²). Do not apply pitch again to dimensions measured on the roof surface.
Add the planes using the same shingle product, apply the chosen waste percentage, then round up to whole bundles. Different products are rounded separately. A roofing square is 100 ft². Starter and cap products use linear coverage rather than square feet.
Example: 40 × 30 ft projection, 6:12 pitch
The sloped area is about 1,341.64 ft². With 10% waste, allow 1,475.80 ft². At exactly 3 bundles per square, buy 45 bundles, providing 1,500 ft² of nominal coverage. This example excludes starter, caps and other roof-system components.
Does every roof use three bundles per square?
No. Bundle coverage varies by product. Use an exact bundles-per-square specification or the stated area coverage. Do not estimate coverage from the number of individual shingles in a bundle.
Is this a complete roof installation specification?
No. This estimates entered shingle and accessory quantities. It does not calculate waterproofing, underlayment laps, valley treatment, ventilation, fastening, structural capacity or code compliance. Confirm roof suitability and the complete system with the manufacturer and installer.
Source: IKO’s guide to roof area, bundle coverage and accessories. For framing geometry, use the rafter length calculator.
