Truss Dimensions Calculator
Truss dimensions are the full set of measurements needed to build or order a truss: top chord (rafter) length, bottom chord length, overall height, and overhang. Enter your span, pitch, and overhang below and this calculator returns every dimension at once, in feet or meters.
Calculate Your Truss Dimensions
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 Dimensions Define a Truss?
A complete truss dimension set has four numbers: span (wall-to-wall width), top chord length (the sloped rafter member, found from rise and run), bottom chord length (equal to span for a standard flat-bottom truss), and overall height (rise from wall plate to ridge, plus any heel height).
Overhang adds to the top chord length beyond the wall but does not change the span or bottom chord — it is measured separately and added at the eave. Truss depth (the vertical distance between top and bottom chords) is a fifth dimension set by the engineer based on span and load, not by geometry alone.
Getting these dimensions right before ordering avoids the most common truss delivery problem: a truss that is dimensionally correct on paper but does not match actual as-built wall spacing on site. Always field-verify span before finalizing an order with your supplier.
Frequently Asked Questions
What dimensions do I need to order a truss?
A truss supplier needs span (building width), pitch, overhang, truss spacing, and roof type at minimum. This calculator returns the resulting chord lengths and overall height so you can cross-check a quote before ordering.
Is bottom chord length the same as span?
For a standard truss with a flat, horizontal bottom chord, yes — bottom chord length equals span. Scissor and attic trusses, which have a sloped or raised bottom chord, are the exception.