A 6-in-12 pitch rises 6 inches for each 12 inches of run.
In the workshop · Calculate · Browser-local
Roof Pitch & Rafter Calculator
Turn a useful pair of roof measurements into a clear planning estimate and responsive roof-triangle diagram.
Roof layout estimate
Give it one valid pair; get the whole triangle.
Choose the measurements you have. This browser-local calculator keeps the convention and units visible instead of guessing at missing dimensions.
Conventions and limits
Clear geometry, not structural advice.
Pitch is rise per 12 units of horizontal run (for example, 6:12). Angle is measured above horizontal. Span means the full eave-to-eave horizontal width, so this symmetric triangle uses span ÷ 2 for the shown run. Rafter length uses √(rise² + run²), angle uses arctan(rise ÷ run), and results round to three decimal places for display. These are planning estimates only—not structural, code, load, connection, overhang, birdsmouth, material, cut-list, permit, or installation guidance. Confirm the actual design with a qualified professional and local requirements.
A couple of useful details
Turn two measurements into a clearer roof triangle.
Choose the measurement pair you have, enter the values, and see the derived pitch, angle, span, and rafter estimate beside a labelled diagram.
No. It is a planning estimate based on the entered roof geometry, not a structural, code, load, or cut-list recommendation.