Formula used
Rafter length = (horizontal run + horizontal overhang) × √(run² + rise²) ÷ run
Worked roof truss example
Roof Truss Calculator example: The basic slope factor is √(8.64² + 5.02²) ÷ 8.64 = 1.1565. Applying it to 9.64 ft of horizontal run gives 11.15 ft (133.79 in).
Use chord length as geometry, not design
Use the value only to understand roof geometry or check an overall slope length before obtaining engineered truss drawings.
Truss design information still required
Heel height, bearing, chord splices, web configuration, camber, overhang detail, and manufacturer design all affect an actual truss.
Questions specific to this calculation
Does this calculator design a roof truss?
No. It only returns the sloped line length associated with the entered run, rise, and overhang. It does not determine truss geometry, member sizes, panel points, plates, webs, bracing, reactions, or load capacity.
Why can a truss drawing disagree with the line-length result?
Heel height, bearing location, overhang detail, chord depth, raised heels, profile breaks, and manufacturer geometry can shift the actual chord and cut dimensions. Use the engineered truss submittal for fabrication and installation.