How to estimate rebar for a simple member

Bar counts from spacing and cover, tie cut length, and what this kind of estimate leaves out.

A bar bending schedule is prepared from the structural drawings. A quantity estimator is the step before that: enough to see the order of magnitude of steel in a slab, beam or column.

Bars in a slab

For bars spaced across a span, the count is floor((span − 2 × cover) / spacing) + 1. The span and the spacing must use the same units. Spacing is centre to centre. The straight bar length used here is the span minus cover at each end. Hooks, cranks and laps are extra and have to be added from the drawing.

Ties

A rectangular tie is estimated as twice the inner width plus twice the inner depth, plus 24 tie-diameters for two hooks. The number of ties is floor((member length − 2 × cover) / spacing) + 1. Inner dimensions are the section size minus cover on both faces.

Weight then uses the same 7850 kg/m³ round-bar formula as the steel weight calculator. Add a wastage percentage only as an allowance for ordering. It is not a substitute for the schedule.