Construction & Materials
Roof Pitch Calculator
Roof Pitch — it works from rise over run: pitch = rise ÷ run (as x-in-12), angle = arctan(rise ÷ run), and slope factor = √(rise² + run²) ÷ run. This page runs that same calculation on your numbers, in your browser: no signup, no uploads, nothing stored.
Enter your rise and run and Roof Pitch Calculator works out the pitch ratio, angle in degrees, slope factor and grade with rise-over-run geometry — fast, free and private, with no sign-up or uploads.
Estimate only. Roof-pitch results depend on the measurements you enter — measure safely and double-check before ordering materials or making structural decisions.
About this calculator
It works from rise over run: pitch = rise ÷ run (as x-in-12), angle = arctan(rise ÷ run), and slope factor = √(rise² + run²) ÷ run. It matters before you buy: a clean volume estimate plus a waste allowance beats a guess every time. Here is the calculation on real numbers: A roof rising 3 m over a 6 m run has a pitch of 3 ÷ 6 = 0.5, i.e. a 26.6° slope (arctan 0.5) or '6 in 12'. For your own figures, use the calculator above — same method, your inputs, computed on-device.
How to use
- Enter the rise in inches.
- Enter the run in inches, usually 12.
- Read the pitch shown as a ratio over the run.
- Tap Calculate to see the angle, slope factor, and grade.
Why use the Roof Pitch Calculator
Instant
Every quantity is worked out on your device the moment you tap Calculate.
Private
The numbers you enter stay in your browser and are never uploaded or saved.
Free
No signup, no paywall, and no ads placed inside your results.
Works offline
Once the page has loaded it keeps working on a weak or dropped connection.
Mobile-first
Laid out for phones and tablets on site just as much as for desktops.
Measure on site
Results assume the exact rise and run you enter; measure carefully on site, since small errors change the pitch and any later material take-off.
Common uses
Use it for choosing the right roofing material
Use it when measuring a roof's pitch
Use it for ordering rafters and trusses
Use it for quick rise-over-run checks
Use it for loft and attic conversions
Use it for snow-load and runoff checks
Technical notes
Roof Pitch Calculator works from rise over run: pitch = rise ÷ run (as x-in-12), angle = arctan(rise ÷ run), and slope factor = √(rise² + run²) ÷ run.
Results assume exact, idealised shapes; real-world measurement error is not included.
The tool works offline once loaded, since every computation is client-side.
Worked example
A roof rising 3 m over a 6 m run has a pitch of 3 ÷ 6 = 0.5, i.e. a 26.6° slope (arctan 0.5) or '6 in 12'.
FAQ
Is the Roof Pitch Calculator a framing design tool?
No. It converts pitch to angle, slope, and grade for reference and is not a structural or framing design.
Does the Roof Pitch Calculator send my numbers anywhere?
No. The Roof Pitch Calculator runs in your browser and nothing you enter is uploaded.
What is the slope factor used for?
Multiply a horizontal run by the slope factor to get the rafter length along the slope.
How is the angle worked out?
The angle is the arctangent of the rise divided by the run, expressed in degrees.