Roof Shingle Calculator — Free Online Tool
Shingles are sold by the bundle, roofs are measured in “squares” (100 sq ft), and pitch makes the real area bigger than the footprint. This roof shingle calculator ties it all together with your roof's slope factored in.
What is the Roof Shingle Calculator?
Three bundles make one square for standard 3-tab shingles (architectural shingles sometimes need 3–4 bundles per square — check the wrapper). The pitch factor adjusts footprint area to true roof area: 1.0 for flat, ~1.15 for a typical 6/12 pitch, up to 1.4+ for steep roofs. Measure each roof plane separately and add them.
The 10% waste covers starter strips, ridge caps, valleys, and cutting around vents — complex roofs with many valleys need 15%. Don't forget underlayment, drip edge, and nails in your buy list. This roof shingle calculator gives bundles and squares; a roofing supplier can convert that into pallets for delivery.
How to use this calculator
- Measure each roof plane (length × width) and total the footprint.
- Find your pitch factor (1.15 is typical; use our roof pitch calculator).
- Enter the numbers and click Calculate Shingles.
- Add underlayment, drip edge, ridge caps, and nails to the order.
Formula
Frequently asked questions
What is a roofing square?
100 square feet of roof area — the unit roofers and suppliers use. This roof shingle calculator converts your dimensions into squares.
How many bundles per square?
Three bundles per square for standard 3-tab shingles; architectural shingles may need more — check the wrapper.
How do I find my roof's pitch factor?
Measure rise and run, then use our roof pitch calculator — it gives the slope multiplier directly.
How much waste for a complex roof?
Plan 15% for roofs with multiple valleys, dormers, and penetrations; 10% for simple gables.