Roof Truss Calculator
Calculates rafter length and the estimated number of roof trusses needed based on roof dimensions and truss spacing.
Roof Truss Calculator gives you a faster way to work through practical calculation scenarios without rebuilding the same calculation from scratch every time. Start with Roof Length (ft), Roof Width (ft), Roof Pitch (rise/12), and Truss Spacing (in) and use the live outputs to estimate Number of Trusses and Rafter Length (ft) in one pass. This page is built to help you compare scenarios quickly, validate rough assumptions, and move into a related calculator when you need a second angle on the same problem.
Use The Calculator In A Few Steps
Work through the inputs deliberately, then compare outputs instead of relying on a single scenario.
Scenario Checks
Use these examples to verify the behavior of the calculator before you run your own values.
What Users Usually Need Next
Keep the calculator open while you skim these answers so you can test the scenario that matters.
Related Calculators
These links are chosen to deepen the session and answer the next likely question without sending the user back to search.
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Converts a decimal inch measurement into its equivalent fractional representation (inches and fractions of an inch).
Taper Calculator
Calculates the taper length and angle based on the large diameter, small diameter, and taper length.