Carpentry Calculators

Rafter Length Calculator

Calculate rafter length from span and roof pitch.

Rafter length
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How this calculator works

Does not include overhang, birdsmouth, ridge deduction, or tail cut.

For best results, measure actual field dimensions, use supplier-specific coverage, and choose a waste allowance that matches the work conditions.

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FAQ

What is the rafter length calculator used for?

Calculate rafter length from span and roof pitch.

Should I add waste or overage?

Yes. Most jobsite estimates should include a reasonable waste factor for cuts, spills, compaction, breakage, or field variation.

Is this a final bid number?

No. Use it as a planning estimate and verify local material coverage, code requirements, and supplier specifications before ordering.