Convert roof pitch between rise:12, degrees, and percent.
Enter pitch as rise over 12, an angle in degrees, or a percentage — get all three plus the slope multiplier used to size materials.
Roof Pitch Calculator
Not sure of your pitch? Find it visually
drag the slider · or measure it with a levelThis is one of six interlinked roofing calculators. For a complete material list across a multi-plane roof, use the full roofing material calculator.
The pitch calculator converts roof slope between rise:12, degrees, and percent grade, and gives the slope multiplier used to size every material. If you don't know your pitch, the visual helper above measures it for you.
How to use this calculator
- Rise (per 12 run)
- Inches the roof rises over a 12-inch horizontal run. A 6-inch rise is a 6:12 pitch. This is the standard way US roofers express slope.
How we calculate it
Degrees = arctangent(rise ÷ 12), converted from radians. A 6:12 pitch is arctan(0.5) = 26.57°.
Percent grade = (rise ÷ 12) × 100. A 6:12 pitch is a 50% grade — percent and the rise:12 fraction are two ways of writing the same ratio.
Slope multiplier = √(12² + rise²) ÷ 12. This is the number that scales footprint area into true roof area, so it's the bridge between pitch and materials.
A worked example
A roof measured at a 6-inch rise over a 12-inch run (6:12).
- Degrees = arctan(6 ÷ 12) = arctan(0.5) = 26.57°.
- Percent = (6 ÷ 12) × 100 = 50%.
- Multiplier = √(144 + 36) ÷ 12 = √180 ÷ 12 = 1.118.
A 6:12 pitch equals 26.57°, a 50% grade, and a 1.118 slope multiplier — so a roof at this pitch has 11.8% more surface than its footprint.
Frequently asked questions
What's a “normal” roof pitch?
Most residential roofs fall between 4:12 and 9:12. Below 2:12, asphalt shingles aren't rated and a membrane roof is needed; above 12:12 the roof is steeper than 45°.
How do I measure pitch without climbing up?
Hold a level against a rafter in the attic, mark 12 inches, and measure straight down to the roof — that drop in inches is your rise. The visual helper above walks through it.
Why does pitch change my material total?
A steeper roof has more surface area for the same footprint, so it needs proportionally more of every material. The multiplier captures exactly how much.