Roof Pitch Chart: Pitch, Angle, Slope Percent and Roof Area Factor
Part of the project planner: Planning a roof replacement.
A roof pitch of 6/12 rises 6 inches for every 12 inches of horizontal run, which is an angle of 26.6° and a 50% slope. The roof area is the footprint times the pitch factor, here 1.118. The roof pitch calculator finds the pitch, the angle and the rafter length from the rise and the run.
Roof pitch chart
For each pitch, the angle, the slope as a percentage, the factor to turn the footprint into the roof area, and the area of a 1,500 sq ft footprint:
| Pitch | Angle | Slope | Area factor | Roof area for 1,500 sq ft |
|---|---|---|---|---|
| 1/12 | 4.8° | 8.3% | 1.003 | 1,505 sq ft |
| 2/12 | 9.5° | 16.7% | 1.014 | 1,521 sq ft |
| 3/12 | 14.0° | 25.0% | 1.031 | 1,546 sq ft |
| 4/12 | 18.4° | 33.3% | 1.054 | 1,581 sq ft |
| 5/12 | 22.6° | 41.7% | 1.083 | 1,625 sq ft |
| 6/12 | 26.6° | 50.0% | 1.118 | 1,677 sq ft |
| 7/12 | 30.3° | 58.3% | 1.158 | 1,737 sq ft |
| 8/12 | 33.7° | 66.7% | 1.202 | 1,803 sq ft |
| 9/12 | 36.9° | 75.0% | 1.250 | 1,875 sq ft |
| 10/12 | 39.8° | 83.3% | 1.302 | 1,953 sq ft |
| 11/12 | 42.5° | 91.7% | 1.357 | 2,035 sq ft |
| 12/12 | 45.0° | 100.0% | 1.414 | 2,121 sq ft |
Types of roof by pitch
| Type | Pitch | Notes |
|---|---|---|
| Low slope | 2/12 to 4/12 | Needs a special underlayment or a membrane roof. |
| Conventional | 4/12 to 9/12 | The most common: a roof you can walk on up to about 6/12. |
| Steep | Over 9/12 | Sheds snow and rain fast, but is dangerous to work on and takes harnesses. |
How to measure the pitch
- From the attic: hold a level horizontally against a rafter, measure 12 inches along it and then the vertical distance up to the rafter. That vertical distance is the rise.
- From the ground: use a pitch gauge or a smartphone app, or measure the gable end of the roof.
- From the plans: the pitch is often shown as a small triangle with the rise over 12.
- Do not climb a steep or wet roof to measure it.
Why the pitch matters
- Roofing quantity: a steeper roof has more area, so more shingles. See the roofing calculator and the roofing squares guide.
- Roofing choice: low slopes need special materials, and steep roofs need more fasteners and safety gear.
- Rafters: the length of a rafter depends on the span and the pitch. See the rafter length chart.
- Snow and water: steep roofs shed them faster.
Roof work is dangerous. Use a harness on any steep roof, and hire a roofer if you are not sure.
Frequently asked questions
What is a 6/12 roof pitch in degrees?
26.6 degrees. A 6/12 pitch rises 6 inches for every 12 inches of horizontal run, which is a 50% slope.
How do you calculate roof pitch?
Divide the rise by the run and express it as inches of rise per 12 inches of run. A roof that rises 8 inches over a 24 inch run has a pitch of 4/12.
How much bigger is a pitched roof than the floor under it?
Multiply the footprint by the pitch factor, the square root of 1 + (rise ÷ 12)²: 1.118 for a 6/12 pitch, so a 1,500 sq ft footprint has a 1,677 sq ft roof.
What is the minimum pitch for asphalt shingles?
Usually 2/12, with a double layer of underlayment for pitches between 2/12 and 4/12. Below 2/12 you need a membrane roof. Check the shingle maker and your code.
What is a common roof pitch?
Between 4/12 and 9/12 for most homes. A 6/12 pitch is the most common, and it can be walked on with care.
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Estimates only. Quantities depend on your materials, site and supplier. Confirm important numbers before you order, and follow local building codes for anything structural.