Joist span calculator

Max span
Cantilever max

IRC-table approximation. Always consult IRC 2024 Table R502.3.1 or a structural engineer for actual code-compliant spans.

About this tool

Joist span calculator is a single-purpose utility on instant.tw, a free toolbox of calculators, converters, generators, and quick lookups. Everything works in your browser — nothing is uploaded, nothing is stored on a server unless explicitly noted.

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