How this calculator works
Calculate common-rafter length from horizontal run, rise and eave overhang.
rafter = √[(run + overhang)² + adjusted rise²]
Roofing · Calculator
Calculate common-rafter length from horizontal run, rise and eave overhang.
Calculate common-rafter length from horizontal run, rise and eave overhang.
The calculator uses the following core relationship:
Estimating note: Actual material quantities can vary with site conditions, detailing, product dimensions, installation method, and waste.
A rafter length calculator estimates roof rafter dimensions from roof rise and run.
Roof pitch and design requirements determine final rafter dimensions.
Engineering note: Use these calculations for estimation and planning. Always confirm final designs according to project requirements and applicable standards.
Calculate common-rafter length from horizontal run, rise and eave overhang.
The calculator uses inputs such as Horizontal run (m), Vertical rise (m), and Horizontal overhang (m). Use values from your drawings, measurements, product data, or project specifications.
Use outputs such as Rafter length, Roof angle, and Slope factor for estimating and cross-checking. Before purchasing or construction, confirm the dimensions, units, waste factors, supplier packaging, and project specifications.
Continue your estimate with related Construction Calc Lab.