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Complete roof pitch chart: degrees, slope %, area multiplier, and rafter length for every pitch from 1/12 to 24/12. Free reference for contractors.
| Pitch | Degrees | Slope | Area multiplier | Rafter / 12 in run |
|---|---|---|---|---|
| 1/12 | 4.76° | 8.3% | 1.0035 | 12.042 in |
| 2/12 | 9.46° | 16.7% | 1.0138 | 12.166 in |
| 3/12 | 14.04° | 25.0% | 1.0308 | 12.369 in |
| 4/12 | 18.43° | 33.3% | 1.0541 | 12.649 in |
| 5/12 | 22.62° | 41.7% | 1.0833 | 13.000 in |
| 6/12 | 26.57° | 50.0% | 1.1180 | 13.416 in |
| 7/12 | 30.26° | 58.3% | 1.1577 | 13.892 in |
| 8/12 | 33.69° | 66.7% | 1.2019 | 14.422 in |
| 9/12 | 36.87° | 75.0% | 1.2500 | 15.000 in |
| 10/12 | 39.81° | 83.3% | 1.3017 | 15.620 in |
| 11/12 | 42.51° | 91.7% | 1.3566 | 16.279 in |
| 12/12 | 45.00° | 100.0% | 1.4142 | 16.971 in |
| 13/12 | 47.29° | 108.3% | 1.4743 | 17.692 in |
| 14/12 | 49.40° | 116.7% | 1.5366 | 18.439 in |
| 15/12 | 51.34° | 125.0% | 1.6008 | 19.209 in |
| 16/12 | 53.13° | 133.3% | 1.6667 | 20.000 in |
| 17/12 | 54.78° | 141.7% | 1.7341 | 20.809 in |
| 18/12 | 56.31° | 150.0% | 1.8028 | 21.633 in |
| 19/12 | 57.72° | 158.3% | 1.8727 | 22.472 in |
| 20/12 | 59.04° | 166.7% | 1.9437 | 23.324 in |
| 21/12 | 60.26° | 175.0% | 2.0156 | 24.187 in |
| 22/12 | 61.39° | 183.3% | 2.0883 | 25.060 in |
| 23/12 | 62.45° | 191.7% | 2.1619 | 25.942 in |
| 24/12 | 63.43° | 200.0% | 2.2361 | 26.833 in |
Roof pitch is written as inches of vertical rise for every 12 inches of horizontal run. A 6/12 roof rises 6 inches across a 12-inch run, which equals a 26.57-degree angle, a 50% slope, and a 1.1180 area multiplier.
Multiply the flat roof footprint by the area multiplier to estimate actual roof surface before waste. Use the rafter column as the diagonal length for a 12-inch run, then scale it to the building's half-span. Eaves, overhangs, hips, valleys, dormers, and waste still need separate takeoff allowances.
Low-slope assemblies, asphalt shingles, tile, metal panels, and slate each have different minimum-slope rules. Confirm the manufacturer's installation instructions and local code before selecting a roof covering from pitch alone.
Method
Roof pitch is written as rise over a 12-inch run, so a 4/12 roof climbs 4 inches vertically for every 12 inches horizontally. The same slope can be expressed as an angle in degrees, as a slope percentage, or as the multiplier that converts flat footprint area into actual sloped surface area.
This chart lists those expressions side by side. The multiplier is the value estimators reach for most often: measured footprint area times the multiplier gives sloped roof area before any waste, overhangs, hips, valleys, or dormers are added.
Hold a level horizontally against the roof, mark 12 inches along it, and measure straight down to the roof surface at that mark. That vertical measurement in inches is the rise.
Find the rise in the chart to get the angle in degrees, the slope percentage, and the pitch multiplier for that pitch.
Multiply the flat footprint area by the pitch multiplier. A 2,000 square foot footprint at 6/12 becomes about 2,236 square feet of sloped surface.
Overhangs, eaves, hips, valleys, dormers, ridge and starter courses, and waste all sit outside this conversion and still need separate takeoff allowances.
A 4/12 pitch is 18.43 degrees. The angle is the arctangent of 4 divided by 12, which also equals a 33.3 percent slope and a pitch multiplier of 1.054.
It converts flat footprint area into actual sloped roof surface area. Multiply the footprint by the multiplier for the pitch: at 6/12 the multiplier is 1.118, so a 2,000 square foot footprint covers about 2,236 square feet of roof surface.
Roofs below 2/12 are generally treated as low slope and typically require membrane systems rather than shingles. Between 2/12 and 4/12 many shingle manufacturers require additional underlayment. Confirm the requirement against the manufacturer specification and local code rather than the pitch alone.
Yes. When rise equals run the angle is exactly 45 degrees, the slope is 100 percent, and the pitch multiplier is 1.414, the square root of two.
Separate plan workflow
This calculator solves one bounded formula from the inputs shown. BuildVision AI supports reviewed plan takeoff, complete-document CSV, and editable quote lines; the estimator owns pricing and final bid approval.