Rebar Lap / Splice Length Calculator

Find the overlap needed to splice two bars. Pick the bar size, steel and concrete grade and the lap type — the tool returns the lap length in mm and as a multiple of diameter.

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How to use: Rebar Lap / Splice Length Calculator

Select the bar size.
Choose steel and concrete grade.
Pick tension or compression lap.

Formula

Tension lap = max(Ld, 30d); compression lap = max(Ld, 24d), where Ld is the development length.

See the full rebar weight chart (kg/m & lb/ft) →

Rebar Lap / Splice Length Calculator — FAQ

What is lap length of rebar?

The overlap between two spliced bars so the force transfers through the concrete.

Is lap length 40d or 50d?

It depends on grade and concrete — commonly 40–50d. This tool computes it from Ld.