Work out rebar lap length instantly with clear inputs, formula shown and shareable results.
A lap splice transfers force from one bar to the next through bond with the concrete, so the length needed scales with bar diameter and falls as concrete strength rises. Tension laps are longer than compression laps because the bar end cannot bear directly on the concrete. Codes also impose an absolute floor of 24 diameters or 200 mm.
Lap length
Lap = factor x bar diameter
Minimum
Lap not less than 24 x diameter or 200 mm
Preliminary estimate only. Lap and anchorage lengths must be taken from the governing code and confirmed by a qualified structural engineer.
Lap = factor x bar diameter. A lap splice transfers force from one bar to the next through bond with the concrete, so the length needed scales with bar diameter and falls as concrete strength rises.
No. They should be staggered and located away from points of maximum stress. Many codes also increase the lap where more than half the bars are spliced at one section.
This calculator takes 3 inputs: Bar diameter, Concrete grade, Bar in. The pre-filled defaults are a realistic worked example — replace them with your own site or project figures.