Roof Pitch Calculator

Convert roof pitch to angle, percent slope, slope factor, rafter multiplier, roof rise, and roof area multiplier. Use this roof pitch calculator for rafter layout, roof framing, roof area estimates, roofing material takeoffs, shed roofs, gable roofs, and structural planning.

Calculate Roof Pitch

Roof pitch = rise ÷ run. Angle = arctan(rise ÷ run). Slope factor = √(rise² + run²) ÷ run.
Your result will appear here.

How the roof pitch calculator works

Rise and run:
The calculator divides roof rise by roof run to find the roof slope ratio.

Angle conversion:
The calculator converts pitch into degrees using the arctangent of rise divided by run.

Percent slope:
The calculator converts roof pitch into percent slope by multiplying rise divided by run by 100.

Roof area multiplier:
The calculator uses the slope factor to convert flat plan area into sloped roof area.

Why use a roof pitch calculator?

A roof pitch calculator helps convert between pitch, degrees, percent slope, rafter multiplier, slope factor, roof rise, and roof area.

It can help with rafter layout, roof framing, roof area estimates, roofing material takeoffs, slope comparisons, and preliminary structural planning.

What your result means

Your result shows roof pitch, roof angle, percent slope, slope factor, rafter multiplier, roof run, roof rise, plan roof area, sloped roof area, and roof area increase. These are planning estimates only.

Roof pitch formulas

Frequently asked questions

What does roof pitch mean?

Roof pitch describes how much a roof rises vertically for a given horizontal run. A 6/12 pitch means the roof rises 6 inches for every 12 inches of run.

How do you convert roof pitch to degrees?

Divide rise by run, then take the arctangent of that number. For example, a 6/12 pitch is about 26.57 degrees.

What is roof slope factor?

Roof slope factor is the multiplier used to convert horizontal roof area into sloped roof area. It is also useful as a rafter length multiplier.

What is a common roof pitch?

Many residential roofs fall around 4/12 to 8/12, but the right pitch depends on design, roofing material, climate, drainage, snow, and local code requirements.