Read a roof pitch in any notation

The job

Plans say "6/12", calculators want degrees, and the roof of a shed is described in percent. They are all the same slope — the tool converts between rise/run, degrees, percent, and gives the rafter-length factor used for material takeoffs.

Convert between notations

Enter rise and run in any consistent unit (in, cm, m — it cancels out), plus an optional span for the rafter length. The result converts to degrees, percent, and x-in-12; the slope factor tells you how much longer the sloped edge is than the horizontal run.

• A 6/12 pitch is 26.57°, a 50% grade, and a rafter factor of 1.118.
• The factor multiplies the horizontal run to get the common-rafter length before overhang.

Worked example

For a 12 ft run at 6/12, the rafter is 12 × 1.118 ≈ 13.4 ft plus the overhang allowance.

Where it stops

It converts notations and computes the slope factor only — it does not design rafters, compute loads, or handle hips and valleys. Rise and run are each capped at 1,000 units and the span at 100,000. Local code governs actual framing.