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Rebar spacing and quantity calculator.

Estimate the number of parallel reinforcement bars needed across a strip, the actual spacing achieved, and an order quantity from bar length and diameter.

read the result

Turn a maximum spacing into a count.

First subtract the nominal cover at both edges to obtain the clear reinforcement width. The calculator then adds enough equally spaced bars so the actual spacing does not exceed the requested maximum.

Governing relationships

For clear width Wclear = W - 2c, bar count is n = ceil(Wclear / s) + 1. The achieved spacing is sactual = Wclear / (n - 1) when more than one bar is required.

Order length includes the entered cut length and lap or cutting allowance. Approximate bar mass uses d2 / 162 kilograms per metre for nominal diameter d in millimetres.

Use the result as a quantity screen.

  • One parallel bar direction and equal nominal edge cover are assumed.
  • Hooks, bends, laps, couplers, chairs, anchorage, shape codes, and multiple reinforcement layers are not modelled.
  • Final bar marks, spacing limits, cover, congestion, durability, and anchorage must come from the drawings, code, and project specification.