Roof Pitch Calculator
Find or convert a roof pitch. Enter a pitch in x/12, degrees, or percent to see it in the other forms, or enter the rise and run you measured to find the pitch.
Roof pitch
6/12
Check the highlighted fields to see your result.
- Angle
- 26.57°
- Slope
- 50%
- Pitch factor
- 1.118
Roof area = footprint × this factor
Results are estimates for information only and do not constitute financial, medical, or legal advice.
How roof pitch works
In the US, roof pitch is written as rise over a 12-inch run, like 6/12. Builders in other countries use degrees or a percentage. All three describe the same slope. The pitch factor tells you how much larger the roof surface is than the area it covers.
The formulas
Angle = arctan(rise ÷ 12) · Percent = rise ÷ 12 × 100
Pitch factor = 1 ÷ cos(angle)
Worked example
Convert a 6/12 roof pitch.
- Percent: 6 ÷ 12 × 100 = 50%.
- Angle: arctan(0.5) ≈ 26.57°.
- Pitch factor: 1 ÷ cos(26.57°) ≈ 1.118, so the roof is about 11.8% larger than its footprint.
Frequently asked questions
What does a 6/12 pitch mean?
The roof rises 6 inches for every 12 inches it runs horizontally. That is an angle of about 26.6°, or a 50% slope. Most houses in the US have pitches between 4/12 and 9/12.
How do I measure my roof pitch?
From the attic or a ladder, hold a level horizontally against a rafter or the roof surface, measure 12 inches along the level, and then measure straight up to the roof. That height is the "x" in x/12. You can also enter any rise and run you measure, in any unit.
What pitch do different roofing materials need?
Asphalt shingles usually need at least 2/12 (with extra underlayment below 4/12), metal panels can go lower depending on the product, and flat or low-slope roofs use membranes. Always check the manufacturer's minimum.