Rebar Spacing Calculator

Inputs

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Overall slab, wall panel, footing or rectangular mat length.
ft
Overall slab, wall panel, footing or rectangular mat width.
ft
Distance from each outside edge to the first bar centerline for this takeoff.
in
Target center-to-center spacing for primary bars. Bars run along the mat length and are spaced across the mat width.
in
Use same or custom secondary bars for a two-way mat. Choose none for a one-way takeoff.
Use the supplier or bar-schedule unit weight. In imperial, #4 rebar is commonly about 0.668 lb/ft.
lb/ft
Length of one purchased rebar stick before cutting.
ft
Added to total straight bar length for offcuts, laps, trimming and ordering allowance. This does not calculate code development length.
%

Results

Default result
Edit inputs
Bars counted
24bars

11 primary + 13 secondary bars.

Also computed

Primary bars11bars

Bars run along the mat length and are spaced across the clear width.

Secondary bars13bars

Bars run along the mat width and are spaced across the clear length.

Actual primary spacingPass11.4in

Actual spacing after rounding up the primary bar count.

Actual secondary spacing11.5in

Actual spacing after rounding up the secondary bar count.

Cut length before waste250ft

Straight bar length before the waste/lap allowance.

Bar length to buy275ft

Includes 10.0% added length.

Method notes 3 notes
  • Primary bars = ceil(clear width / target spacing) + 1. Secondary bars use the same rule across the clear length when enabled.
  • Clear length and width subtract the entered edge cover from both sides.
  • This is a rebar layout and material takeoff only. It does not choose code-required spacing, reinforcement ratio, concrete cover, bar size, lap splice, development length, hooks, dowels, retaining-wall reinforcement, slab thickness, footing design or local permit approval.

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