Roofing Shingles Calculator

Calculate roofing squares, shingle bundles, and nails needed based on your roof footprint and pitch.

Building Length (ft)

Footprint length, measured on the ground.

Building Width (ft)

Footprint width, measured on the ground.

Roof Pitch (rise per 12" run) (/12)

A 6/12 roof rises 6 inches for every 12 inches of run.

Waste Factor (%)

Use 15% for hips, valleys, or cut-up roofs.

This estimates a simple gable roof from ground footprint. For complex rooflines, measure the actual roof planes for a precise count.

Roofers price and order material in "squares" — one square covers 100 square feet of actual roof surface — but homeowners usually only know their building's ground footprint, not the sloped roof area, which is always larger. This calculator bridges that gap using the pitch multiplier: a steeper roof has more actual surface area than its footprint suggests, so a 6/12 pitch adds about 12% more area than the flat footprint, and steeper pitches add proportionally more.

Once the roof area in squares is known, standard 3-tab or architectural shingles need 3 bundles per square, and roofing nails run about 320 per square for a standard 4-nail-per-shingle pattern — both scaled up here by your waste factor to account for cuts, hips, and ridge caps.

Frequently Asked Questions

How many bundles of shingles are in a square?

Most architectural and 3-tab shingles are packaged 3 bundles per square (100 sq ft), though some heavier or designer shingles use 4-5 bundles per square — check the product packaging.

How do I convert roof pitch to actual roof area?

Multiply the flat footprint area by a pitch multiplier: sqrt(1 + (rise/12)^2). For a 6/12 roof that multiplier is about 1.118, meaning the real roof surface is about 12% larger than the footprint.