What's the difference between a bundle and a roofing square?

A roofing square is 100 sqft of roof area. Standard 3-tab shingles come 3 bundles to a square, so this calculator divides actual roof area by 100 and multiplies by 3 to get bundles needed.

Why does a steeper pitch need more shingles for the same footprint?

A sloped roof surface is always larger than its flat footprint. The steeper the pitch, the greater the slope factor applied, so the actual roof area (and shingles needed) increases even though the footprint stays the same.

Roofing Calculator

Calculate actual roof area and shingle bundles needed, accounting for pitch.

How this is calculated

Actual roof area = footprint × √(1 + (rise/run)²) × (1 + waste%). Bundles = (area ÷ 100) × 3

Assumptions used in this calculation

Bundle coverage: Assumes standard 3-tab shingles at 3 bundles per 100 sqft (1 roofing square).

About this calculator

Calculates the actual (sloped) roof surface area from footprint area and pitch, then converts to roofing squares and shingle bundles needed, including a waste allowance.

Worked example

1500 sqft footprint, 6:12 pitch, 10% waste

Result: ≈ 56 bundles needed

Was this helpful?

Frequently asked questions

Slope Calculator

Calculate slope as a ratio, percentage, angle, or roof pitch from rise and run.

Popular

Construction Cost Calculator

Estimate construction cost from built-up area and rate per square foot.

Roofing Calculator

About this calculator

Frequently asked questions

What's the difference between a bundle and a roofing square?

Why does a steeper pitch need more shingles for the same footprint?

Related calculators