Roof Pitch Calculator

Roof pitch is the steepness of a roof, expressed as rise over run. A 6/12 pitch rises 6 inches vertically for every 12 inches of horizontal run — an angle of about 26.6 degrees.

6/12 is the most common residential pitch in the U.S. Anything between 4/12 and 9/12 is considered conventional.

Two ways. A steeper roof has more surface area — a 12/12 pitch adds 41% over the footprint — and above roughly 7/12 it also requires fall protection and staging, which adds around 15% to labor.

From inside the attic, hold a level horizontally against a rafter, measure 12 inches along it, then measure vertically from that point up to the rafter. That vertical measurement is your rise over 12.

It is the secant of the roof angle — the exact factor by which your roof surface exceeds its footprint. A 6/12 roof has a multiplier of 1.118.

Anything above 7/12 is generally treated as steep, requiring harnesses and staging. Above 9/12, most crews charge a meaningful premium.

Not below 4/12. Standard asphalt shingles rely on gravity to shed water and will leak on a shallower slope. Low-slope roofs need membrane systems instead.

They describe the same steepness. Pitch is conventionally written as rise/12 (6/12); slope may be given as an angle in degrees or a percentage. A 6/12 pitch equals a 26.6° slope.