What is truss span?
Span is the horizontal distance a truss covers between its bearing points, usually from outside wall to outside wall. Everything else, from rafter length to truss depth, follows from it.
Typical spans by chord size
| Chord / truss | Typical span (light residential) |
|---|---|
| 2×4 engineered truss | up to about 30-40 ft |
| 2×6 engineered truss | about 40-60 ft |
| Steel truss | 60 ft and beyond |
These are rules of thumb. Actual limits depend on spacing, pitch, species, grade and load, so always get the final span confirmed by a truss engineer.
How the calculator finds rafter length
rafter = (span ÷ 2 + overhang) ÷ cos(angle)
Switch units between feet and meters at any time. For cost and quantity, move on to the quantity calculator and cost calculator.