Angle and grade
Angle = atan(rise ÷ run) converted to degrees. Percent grade = rise ÷ run × 100.
Free roofing tool
Roof Pitch Calculator
Convert a measured rise and run into pitch ratio, roof angle, percent grade and slope multiplier with source-derived equations.
Inputs
Enter rise and run
Use the same units for both values. A 12-inch run is common, but other positive run values are supported.
Conversion method
Slope multiplier
Multiplier = √(run² + rise²) ÷ run. Results display angle and grade to two decimals and multiplier to three.
Use measured rise and run from a reliable field, plan or aerial source. This converter does not determine roof condition or replace verification.
Worked example
A 6/12 pitch converts to 26.57°, 50.00% grade and a 1.118 pitch multiplier. Multiplying a flat footprint by 1.118 estimates sloped area.
Roof pitch calculator FAQ
How is pitch converted to degrees?
The source formula uses arctangent of rise divided by run, then converts radians to degrees.
What is percent grade?
Percent grade is rise divided by run multiplied by 100. A 6/12 pitch is 50% grade.
What is the pitch multiplier?
It is sqrt(run² + rise²) divided by run and can convert a flat footprint to estimated sloped area.
Is 12/12 equal to 45 degrees?
Yes. Equal rise and run produce a 45-degree angle and approximately 1.414 multiplier.