Roof Pitch Calculator

Convert between roof pitch (rise:run), angle in degrees, and slope percentage. Includes rafter length and total roof area for any building width.

What Is Roof Pitch?

Roof pitch is the ratio of vertical rise to horizontal run, expressed as "X:12" — for example, "6:12" means the roof rises 6 inches for every 12 inches of horizontal run. It's the standard way roofers describe how steep a roof is.

Standard Roof Pitches

Low Slope (2:12 to 4:12)

Common on modern homes, sheds, and porches. Requires special low-slope roofing materials — standard shingles may leak. Often uses membrane or rolled roofing.

Conventional Slope (4:12 to 9:12)

The most common range for residential roofs. Standard asphalt shingles work well. Walkable for most contractors.

Steep Slope (9:12 and above)

Common on Victorian and Tudor homes. Requires special safety equipment. Materials often need additional fastening. Higher labor cost.

Frequently Asked Questions

What is a 6/12 pitch in degrees?

A 6:12 pitch equals 26.57 degrees. Use the formula: angle = arctan(rise ÷ run). For 6:12: arctan(6/12) = arctan(0.5) = 26.57°.

How do I measure roof pitch without climbing up?

Hold a level horizontally against the gable end (in the attic) and measure down to the roof surface at 12 inches. The distance in inches is your rise, and 12 is your run — so a measurement of 6 inches means a 6:12 pitch.

How do I calculate roof area from pitch?

Multiply the footprint area by the pitch multiplier. For 6:12 pitch, the multiplier is 1.118. So a 1,000 sq ft footprint becomes 1,118 sq ft of roof surface.