DATUM

Roof Pitch Converter

Convert roof pitch between rise-per-12, degrees, percent and rafter multiplier, and get rafter length for any run.

Roof Pitch Converter

Pitch, angle, percent and rafter length are four ways of saying the same thing. Change any one and the rest follow. Pure geometry, so it is the same in every jurisdiction.

Pitch
Angle
Slope
Rafter multiplier
Rafter length (for the run above)
Vertical rise over that run

Definitions: a 6:12 pitch rises 6 units for every 12 of horizontal run. Angle = arctan(rise / 12). Slope % = rise / 12 × 100. Rafter multiplier = √(rise² + 12²) / 12 — multiply the horizontal run by it to get the sloped length. No building code is involved in the arithmetic; roofing material minimum slopes are a separate, manufacturer- and code-specific question.