Building tool
Roof Pitch & Rafter Calculator
Calculate roof pitch, angle, rafter length, and roof area from a few measurements.
Runs in your browserEstimate
- Pitch
- 6 in 12
- Roof angle
- 26.57°
- Common rafter
- 14.53 ft
- Both roof planes
- 872.1 sq ft
- With 10% waste
- 959.3 sq ft
This gives geometric lengths only. Confirm birdsmouth, ridge, local code, and structural sizing with a qualified builder.
How to use this roof pitch & rafter calculator
- Measure the project, enter the dimensions in the units shown, and add the waste, spacing, coverage, or material settings that apply.
- Review the calculated totals, units, and assumptions. Check the inputs and units before relying on the result.
- Change one input at a time to compare another case, then copy or save the result you plan to use.
About this roof pitch & rafter calculator
Use the Roof Pitch & Rafter Calculator to calculate roof pitch, angle, rafter length, and roof area from a few measurements. Each control affects a specific part of the result.
You can also use it to compare results after changing one input.
Example
A roof with a 12-foot run and 6-foot rise has a 6-in-12 pitch. Add the building length and overhang to estimate rafter length and roof area.
Common uses
- → calculate roof pitch, angle, rafter length, and roof area from a few measurements
- → compare results after changing one input
- → save an estimate for planning or comparison