Roof pitch calculator

Convert rise and run into roof pitch, angle and slope, or an angle into pitch, and work out the real roof area and roofing squares.

Roof pitch chart

Questions

What is roof pitch?

Roof pitch is how many inches the roof rises for every 12 inches it runs horizontally. A 6/12 pitch rises 6 inches per foot. It can also be given as an angle (26.57° for 6/12) or a slope percentage (50%).

How do I measure roof pitch?

Hold a level horizontally against the roof or a rafter, measure 12 inches along it, then measure straight up from that point to the roof. That height in inches is the pitch over 12. You can also measure any rise and run and enter both here.

How do I convert pitch to degrees?

Divide the rise by the run and take the inverse tangent. For 6/12, 6 ÷ 12 = 0.5, and the inverse tangent of 0.5 is 26.57°.

What is a roof pitch multiplier?

It converts flat footprint area into actual sloped roof area: multiplier = √(1 + (rise ÷ run)²). For a 6/12 roof it is 1.118, so a 1,500 sq ft footprint has about 1,677 sq ft of roof.

What is a roofing square?

Roofing materials are sold by the square: 100 square feet of roof surface. A 1,677 sq ft roof is 16.77 squares. Suppliers usually add 10–15% for waste and cutting.

What is the most common roof pitch?

In the US, pitches between 4/12 and 9/12 are most common on houses. Below 4/12 is generally considered low slope, which needs different roofing materials.

Roof area from the footprint assumes a simple roof of one pitch and doesn't include overhangs. Measure and allow for waste before ordering materials.