Free Tool
Roof Squares & Shingle Calculator
Enter your roof's dimensions and pitch to estimate roofing squares and shingle bundles needed.
Measure at the roof edge (eaves), not the exterior walls — a roof always overhangs the walls, and that difference is the most common reason a footprint-based estimate comes up short. If you only have wall dimensions, add the overhang above and it’ll be included. For a roof with multiple sections, add each section’s area together first.
Roof complexity (waste factor)
Some hips or valleys
Shingle type
3-tab or standard architectural shingles
Enter your roof’s footprint area and pitch above to see your results.
This estimates field shingles only — starter strips and ridge caps are ordered separately. For underlayment, take the “Roofing squares” number above (not the waste-adjusted one — the Roofing Underlayment Calculator applies its own waste factor, and starting from a number that already has waste built in would double it up). Treat this as a planning estimate, not a final material order.
What is a roofing square?
A roofing square is 100 square feet of roof surface — the standard unit roofers use for pricing, ordering material, and estimating labor. It’s not the same as your house’s floor plan square footage: because roofs are sloped, the actual roof surface is larger than the flat footprint beneath it.
How to measure your roof pitch
Roof pitch is expressed as inches of rise per 12 inches of horizontal run — a “6/12” pitch rises 6 inches for every 12 inches you move horizontally. To measure it: hold a level horizontally against the roof surface (or in the attic, against a rafter), measure exactly 12 inches along the level, then measure straight down from that 12-inch mark to the roof surface. That vertical measurement, in inches, is your rise — the number to enter above. Measure it directly rather than estimating by eye — misjudging a pitch by even one step (say, calling an 8/12 a 6/12) understates the whole roof’s area by several percent. If you only have an angle reading (from a digital angle finder or level app) rather than a rise and run, the Roof Pitch Calculator converts it to X/12 for you.
| Pitch | Multiplier |
|---|---|
| 2/12 | 1.014 |
| 3/12 | 1.031 |
| 4/12 | 1.054 |
| 5/12 | 1.083 |
| 6/12 | 1.118 |
| 7/12 | 1.158 |
| 8/12 | 1.202 |
| 9/12 | 1.250 |
| 10/12 | 1.302 |
| 11/12 | 1.357 |
| 12/12 | 1.414 |
How many shingle bundles come in a square?
Standard 3-tab and most architectural shingles are packaged 3 bundles per square across every major manufacturer — that’s the default this calculator uses. Heavier premium or designer laminate shingles are often packaged more bundles per square, commonly 4 or sometimes 5, since a single bundle can only weigh so much before it’s unworkable to carry up a ladder. If you already know your specific product’s coverage, enter it directly under “Know your exact shingle coverage” above for a precise number instead of the preset.
Why you need extra material
No roof gets shingled without waste — cuts along hips, valleys, ridges, and rakes all use partial shingles, and mistakes happen. Roofing estimators commonly plan for about 10% extra on a simple gable roof, 15% on a roof with some hips or valleys, and up to 20% on a complex, heavily cut-up roof. Ordering to the exact raw square count, with no allowance, is how a job runs short of material halfway through.
Worked example
A 40 ft × 30 ft footprint (measured at the eaves), 6/12 pitch, 10% waste, standard shingles:
- 1. Flat footprint: 40 × 30 = 1,200 sq ft
- 2. Pitch multiplier for 6/12: √(6² + 12²) / 12 ≈ 1.118
- 3. Actual roof area: 1,200 × 1.118 ≈ 1,342 sq ft
- 4. Roofing squares: 1,342 / 100 ≈ 13.4 squares
- 5. With 10% waste: 13.4 × 1.10 ≈ 14.8 squares to order
- 6. Shingle bundles: 14.8 × 3 ≈ 45 bundles
Frequently asked questions
What is a roofing square?
100 square feet of roof surface. It's the standard unit roofers use for pricing, material orders, and labor estimates — not the same as a square foot of your house's floor plan.
Why is my roof's actual area bigger than my house's footprint?
Because of the pitch. A sloped surface covers more area than its flat horizontal footprint — the steeper the pitch, the bigger the difference. A 6/12 pitch roof, for example, has about 12% more surface area than the footprint below it.
How many shingle bundles come in a square?
Standard 3-tab and most architectural shingles are packaged 3 bundles per square across every major manufacturer. Heavier premium or designer laminate shingles are often packaged 4 or sometimes 5 bundles per square, since a bundle can only weigh so much to stay workable.
How much extra material should I order?
Roofing estimators commonly plan for about 10% extra on a simple gable roof, 15% on a roof with some hips or valleys, and up to 20% on a complex, cut-up roof — to cover cuts, waste, and mistakes.
What roof pitch is too low for asphalt shingles?
Asphalt shingles generally need a minimum pitch, commonly cited around 2/12 to 4/12 depending on the underlayment used — below that, check your specific shingle manufacturer's installation requirements, since low-slope roofs often need a different roofing system entirely.