Does it calculate every flashing detail?

No. Add flashing, starter, ridge, ventilation, decking and specialty accessories as separate estimate lines.

Why choose a shingle type?

Bundle coverage differs by packaging. The calculator keeps bundles-per-square visible, but you must verify the selected manufacturer's label.

Roofing calculator

Roof shingle calculator

Pitched roof area, squares, type-specific shingle bundles and underlayment rolls.

Calculator result and formula

Shingle bundles to order: 30 bundles

Formula: Footprint × √(1 + (rise ÷ 12)²) ÷ 100 × bundles per square × (1 + waste)

Formula ID: ROOF-SHINGLE-002 · Version 2.0.0.

Inputs

Building length: Horizontal roof length when calculating footprint from dimensions Default: 30.
Building width: Horizontal roof width when calculating footprint from dimensions Default: 20.
Direct footprint area: Optional measured horizontal footprint; enter 0 to use length × width Default: 0.
Common pitch picker: Select a common pitch or use manual rise below Default: 6.
Manual pitch rise: Used only when Custom manual rise is selected Default: 6.
Shingle type: 3-tab normally uses 3 bundles/square; architectural normally uses 4 Default: 4.
Waste factor: Allowance for cuts and roof detail Default: 10.

How this calculator works

This calculator converts a measured horizontal roof footprint into sloped roof area, squares, type-specific shingle bundles and underlayment rolls with a visible allowance.

Enter horizontal building dimensions, or replace them with a measured direct footprint area.
Choose a common pitch or use a manual rise-per-12 value.
Select actual shingle packaging type and adjust allowance for valleys, hips, dormers, cuts and roof detail.

Worked example: Example: a 30 ft × 20 ft roof with a 6:12 pitch has a slope multiplier of about 1.118. Its 600 ft² footprint becomes about 671 ft²; architectural shingles at 4 bundles per square plus 10% allowance round to 30 bundles.

Assumptions and limitations

Pitch uses the selected rise per 12 units of horizontal run.
The direct footprint area, when greater than zero, replaces length × width; it must be a measured horizontal area.
Selected shingle type uses 4 bundles per square; verify manufacturer coverage and packaging.
Underlayment roll coverage is a 1,000 ft² planning assumption before required overlap.

Common questions

Does it calculate every flashing detail?: No. Add flashing, starter, ridge, ventilation, decking and specialty accessories as separate estimate lines.
Why choose a shingle type?: Bundle coverage differs by packaging. The calculator keeps bundles-per-square visible, but you must verify the selected manufacturer's label.

Reference notes

Procore: asphalt-shingle calculation guidance

Related calculators

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