FREE ROOF SHINGLE CALCULATOR

What a roof shingle calculator does

A roof shingle calculator turns roof size and pitch into the number of shingle bundles to order. It measures the roof in squares (one square is 100 square feet), turns those squares into bundles, and adds a waste allowance for cuts, hips, and valleys.

Order short and the crew sits idle waiting on a supply run. Order long and the extra bundles eat your margin. This tool gives you a solid bundle count — plus underlayment, nails, and an install-time estimate — so you can quote and order without padding the number.

How to use this shingle calculator

Size the roof, set the pitch and waste, and read the bundle count. Everything stays in your browser.

1. Enter the roof size. Measure each plane by length × width, or switch to total area if you already have it.
2. Set the pitch. Pick the rise per 12 inches of run. The steeper the roof, the more surface it has above its footprint.
3. Choose a waste allowance. 10% for a simple gable, 15% for most roofs, 20% for cut-up roofs with lots of valleys.
4. Pick the shingle type. Architectural or 3-tab. It sets how many shingles come per bundle.
5. Add price and crew (optional). Enter a price per square and crew size to estimate cost and install time.

How the bundle count is calculated

Three steps take you from a flat footprint to the bundles you order.

Footprint to roof area

A sloped roof is bigger than the footprint it sits on. Multiply the footprint by the pitch multiplier, √(rise² + 12²) ÷ 12, to get the true roof area.

Roof area to squares

Divide the roof area by 100. A roofing square is 100 square feet, the unit roofers and suppliers price in.

Squares to bundles

Asphalt shingles ship 3 bundles to a square. Multiply squares by 3, add your waste, and round up, since you can only buy whole bundles.

Example. A 1,700 sq ft footprint at 6/12 pitch × 1.118 = 1,901 sq ft of roof, or about 19 squares. At 3 bundles per square plus 15% waste, that's 66 bundles.

Architectural vs 3-tab shingles

Both ship 3 bundles to a square, but the shingle count per bundle differs. 3-tab shingles run about 29 per bundle. Architectural (laminate) shingles are larger and heavier, at roughly 21. The bundle count is the same either way. Only the total shingle count changes.

Architectural shingles cost more but last longer and handle wind better, which is why they're the default on most homes now. 3-tab is cheaper and lighter, still common on rentals and budget jobs. Pick the type so the total-shingle count matches what you're ordering.

How to measure a roof

You can measure from the ground, up on the roof, or from satellite imagery. Either way, what you're after is the footprint of each roof plane.

1. Measure each plane. Get the length and width of every roof section, dormers and garages included.
2. Add the planes together. Multiply length × width for each, then add them up for the total footprint.
3. Find the pitch. Use a level and tape, or a pitch-finder app, to get the rise per 12 inches of run.
4. Add waste. More hips, valleys, and dormers mean more cuts, so bump the allowance up.

Frequently asked questions