UtilibyRoof Pitch Calculator
Convert roof pitch between rise/run, degrees and slope percentage. Free, fast and no sign-up.
What is roof pitch?
Roof pitch describes how steep a roof is. It is expressed three ways, and this calculator converts between them:
- Rise/run (X:12) — how many units the roof rises for every 12 units of horizontal run.
- Degrees — the angle of the roof plane from horizontal.
- Slope percentage — rise divided by run, multiplied by 100.
Pitch conversion table
| Pitch (X:12) | Degrees | Slope % | Slope factor |
|---|---|---|---|
| 2:12 | 9.5° | 16.7% | 1.01 |
| 3:12 | 14.0° | 25.0% | 1.03 |
| 4:12 | 18.4° | 33.3% | 1.05 |
| 5:12 | 22.6° | 41.7% | 1.08 |
| 6:12 | 26.6° | 50.0% | 1.12 |
| 7:12 | 30.3° | 58.3% | 1.16 |
| 8:12 | 33.7° | 66.7% | 1.20 |
| 9:12 | 36.9° | 75.0% | 1.25 |
| 10:12 | 39.8° | 83.3% | 1.30 |
| 12:12 | 45.0° | 100.0% | 1.41 |
What is the slope factor?
The slope factor is the number you multiply by the horizontal roof area to get the actual sloped surface area. It matters when ordering shingles, underlayment or metal roofing.
For example, a roof with 1,000 square feet of horizontal footprint and a 6:12 pitch has a slope factor of 1.12, so the actual roof surface is 1,120 square feet.
The slope factor is calculated as: √(rise² + run²) ÷ run.
How to measure roof pitch
- Place a level horizontally on the roof, holding it perfectly level.
- Mark 12 inches along the level from where it touches the roof.
- Measure vertically from that 12-inch mark down to the roof surface.
- The number of inches of rise over 12 inches of run is your pitch.
Common pitch ranges
- Low slope (2:12 to 4:12) — often used on sheds and modern homes. Requires special roofing materials.
- Conventional slope (4:12 to 9:12) — the most common range for residential roofs. Works with standard shingles.
- Steep slope (9:12 and above) — steeper roofs shed water and snow quickly but need extra fastening.
Frequently asked questions
What is a 6/12 roof pitch in degrees?
A 6/12 pitch is approximately 26.57 degrees.
What is the minimum roof pitch for shingles?
Most asphalt shingle manufacturers require a minimum of 4:12 pitch. Below that, you need a double layer of underlayment or a different roofing material.
How do I calculate roof area from pitch?
Measure the horizontal footprint of the roof, then multiply by the slope factor for your pitch. A 6:12 roof has a slope factor of 1.12.
What is a walkable roof pitch?
Most roofing professionals consider 6:12 as the maximum safe walking pitch without special equipment.
Is anything I enter stored?
No. All calculations run in your browser.