Truss Calculator
Estimate roof rise, rafter length, roof angle, truss count, and approximate roof area from your building dimensions and roof pitch.
Enter roof dimensions
Result
Enter the roof dimensions to calculate the truss geometry.
Half-span geometry
A symmetrical gable roof uses half the building span as the horizontal run from the wall plate to the ridge.
Pitch controls slope
A larger rise-to-run value creates a steeper roof, increasing both roof rise and rafter length.
Truss count estimate
The count includes a truss at each end and rounds upward so the spacing does not exceed your entered value.
Frequently asked questions
How is rafter length calculated?
The calculator uses the Pythagorean theorem with the horizontal run, including overhang, and the matching vertical rise.
Does roof area include both sides?
Yes. The estimated area includes both sloped roof planes and includes the entered eave overhang.
Does the truss count include both end trusses?
Yes. It divides the building length by the spacing, rounds upward, and adds one end position.
Can this calculator design a structural truss?
No. It estimates geometry and quantity only. Structural trusses require engineered member, plate, load, and bracing calculations.
Results are estimates generated locally in your browser from standard geometry, material yield and waste assumptions. They are for planning purposes only, not engineering, structural, code or supplier advice. Confirm dimensions, material strength, delivery constraints and local building codes with a licensed professional before purchasing or building. VisionVix accepts no liability for decisions based on this tool's output.
