Roof Pitch Calculator

Roof pitch expresses rise over run — how much the roof climbs vertically for each horizontal foot. A 6:12 pitch rises 6 inches for every 12 inches of run. Pitch affects shingle choice, snow load, and walkability.

The angle in degrees is arctan(rise ÷ run). Steeper roofs shed water faster but cost more to frame and shingle. Enter rise and run in the same units (inches per foot is standard in the US).

Example: 6 inches rise and 12 inches run gives a 6:12 pitch and about 26.6°. A 4:12 pitch (4 rise, 12 run) is roughly 18.4° — common on many residential roofs.

US residential roofs are almost always described as rise:12, so a 6:12 pitch means 6 inches of rise for every 12 inches of horizontal run. Metric countries more often quote the angle in degrees or a percentage slope — 6:12 is about 26.6° or a 50% slope.

Building codes and manufacturer warranties often set minimum pitches. Many asphalt shingles need at least 2:12, and low-slope roofs below that usually switch to membrane systems. Ice and water shield requirements also tighten as pitch drops.

Steeper roofs cost more than the material area alone suggests. Framing lumber, underlayment, and labour all rise with pitch, and above about 6:12 many crews add fall protection; above 8:12 staging or harnesses are common. Local code may require more than the material math shows.

Surface area of a pitched roof exceeds the building footprint by the secant of the pitch angle. A 6:12 roof covers about 12% more area than the plan view, which is why shingle quantity should come from a roofing area calculator rather than floor square footage.

Snow load and walkability both track pitch. Steeper slopes shed snow and water faster but are harder to walk for maintenance; low pitches hold snow and need careful drainage detailing. Confirm both the pitch ratio and the angle before ordering materials.

Pitch also affects walkability and snow load planning — steeper slopes need more safety gear for crews and may trigger local code requirements beyond the material-area math this tool provides.