Roofing
Roof pitch and common rafter length
Your inputs
Complete only the fields for your selected method. Use one consistent job or reporting period. Use zero for a known zero amount only when the field permits it. Missing costs and market rates are not added automatically. Currency selection labels amounts; it does not convert exchange rates.
How this calculation works
rise = run × pitch / 12; line length = hypot(run,rise); sloped overhang = horizontal overhang × hypot(1,rise/run)
Use the horizontal run for one roof plane, not the total building span. These are geometric line lengths before material cuts and allowances. Ridge board thickness, birdsmouth, plumb cuts, load, timber sizing and structural design are outside this model. Use your own records for the same scope and period. Example figures are illustrative, not industry benchmarks. Results exclude income taxes and any cost you have not entered. Check the result before pricing work or committing resources.
What information do I need?
Use records for the same job, equipment or accounting period. Only the fields for your selected entry method are required. An unknown amount is not zero.
Input definitions and where to find them
- What do you know?: Choose the entry method matching the information you have. Only its active inputs are required.
- Horizontal run from bearing reference to ridge reference (ft): Use the matching measured quantity, time log, schedule or clearly stated estimate. Zero means intentionally none; an unknown amount is not zero.
- Pitch rise per 12 inches of run (in): Use the matching measured quantity, time log, schedule or clearly stated estimate. Zero means intentionally none; an unknown amount is not zero. Used with: Pitch (rise in inches per 12 inches of run).
- Measured rise over the entered run (ft): Use the matching measured quantity, time log, schedule or clearly stated estimate. Zero means intentionally none; an unknown amount is not zero. Used with: Measured total rise.
- Additional horizontal overhang beyond bearing reference (ft): Use the matching measured quantity, time log, schedule or clearly stated estimate. Zero means intentionally none; an unknown amount is not zero.
Use the Where to find this value controls beside the inputs for available work-it-out helpers. Estimates remain your assumptions; a helper does not verify the source figures.
Worked example
Example amounts use US dollars (USD).
Example answer: Common-rafter line length through bearing and ridge references is 13.4164 ft for the illustrative inputs below.
Example inputs
- What do you know?: Pitch (rise in inches per 12 inches of run)
- Horizontal run from bearing reference to ridge reference: 12.00 ft
- Pitch rise per 12 inches of run: 6.00 in
- Additional horizontal overhang beyond bearing reference: 1.00 ft
- Common-rafter line length through bearing and ridge references
- 13.4164 ft
- Sloped overhang length
- 1.1180 ft
- Total reference line including overhang
- 14.5344 ft
- Pitch rise per 12 inches of run
- 6.0000 in
- Slope angle above horizontal
- 26.5651 °
These illustrative values are not recommended rates or industry averages. Replace every example input with your own figures.
Use the result well
Inputs come from your own records and stated assumptions; no rates or legal limits are looked up.
Review the entered assumptions and calculator limits before using these results. Have a qualified professional verify design and safety decisions.