Roof Truss Design Calculator
A roof truss design calculator combines every input a truss design needs — span, pitch, spacing, material, and load — into one set of results: dimensions, quantity, weight, and cost. Enter your building specs below for a complete preliminary design.
Design Your Roof Truss
Enter your building specifications below. Results and the roof diagram update live as you type.
Live Roof Diagram
Results
Estimate Your Project Budget
Automatically calculated from your inputs above in the calculator.
Estimates only. Actual costs vary by region, supplier, and site conditions.
What a Full Truss Design Includes
A complete preliminary truss design answers five questions at once: How long are the chords? How tall is the roof? How many trusses does the building need? How much load does each truss carry? What will the material cost? This calculator answers all five from the same set of inputs.
Because every result updates together as you change an input, this design calculator is useful for comparing options quickly — try a steeper pitch to see the rafter length and cost trade-off, or tighter spacing to see the truss count and per-truss load trade-off, without recalculating each number by hand.
For a specific single question — just span, just cost, or just truss type — the dedicated calculators linked below are faster; use this page when you want the full picture in one pass, then move to a stamped engineered design for anything beyond planning.
Frequently Asked Questions
What is included in a roof truss design calculator?
A complete design calculator combines span, pitch, spacing, material, and load into chord dimensions, roof height, truss quantity, total weight, and material cost — everything needed for a preliminary design in one pass.
Is a free online design calculator enough to build from?
No — free calculators like this one are for planning and budgeting. Any permitted structure needs a stamped, engineered truss design from a licensed professional before construction.