Free · Roofing & slopes
Roof Pitch, Angle & Rise Calculator
Convert roof rise and run into pitch and angle, or calculate an unknown dimension.
- Formula & worked example
- Private in your browser
- No signup
Your calculation
Enter enough known values to calculate the blanks.
How to use this calculator
- Enter the values you know in the units shown. Leave unknown values blank.
- Results update automatically as you type. Edit a result to calculate another value, or lock a value to keep it fixed.
- Reset restores the starting fields. A worked example appears below.
Private by default
Inputs and results stay in this browser tab. Bookify does not upload or store the values you enter.
Formula and method
Roof pitch compares vertical rise with horizontal run. The sloping roof length differs from horizontal run; using one in place of the other changes the result.
Pitch per 12 = 12 × rise / run; angle = atan(rise / run)
Worked example
Enter these known values and leave the other values blank.
- Rise
- 3 m
- Run length
- 4 m
- Rafter length
- 5 m
- Roof pitch
- 36.87 deg
- Roof pitch (%)
- 75 %
- Roof pitch (x:12)
- 9 :12
Assumptions and limitations
- Inputs must satisfy the validation rules. Editing a result can recalculate an earlier input; lock values you want to keep fixed.
Common questions
What does this roof pitch calculation tell me?
Roof pitch compares vertical rise with horizontal run. The sloping roof length differs from horizontal run; using one in place of the other changes the result.
Can I calculate a different unknown?
Yes. Clear that field and enter the other known values. The calculator uses the available inverse equations.
References
The calculation equations, inverse formulas, units, and input rules were imported from this source. Bookify provides the interface and equation solver.
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