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Rebar Calculator

Take off slab reinforcement, tie wire and supports from your specified layout.

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ft
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Spacing is both ways. Use your plan’s cover and laps.

Slab plan · grid centre lines

Concrete boundary; steel stays inside cover.

Your slabs

    Enter plan dimensions, cover and spacing.

      Set stock, tie-wire and support details below.

      Grid, stock & laps · #4 / 1 mat / 20 ft

      A lap is required when a run exceeds stock length. Cut packing is an estimate, not a fabrication schedule. Metric display retains the selected US bar.

      Tie wire

      Choose the pattern specified by your placement plan. Pattern choices are counting examples, not tying requirements. Percentage mode does not specify locations. Dots show grid ties on one mat only; splice, support and additional-bar ties are counted separately. The 385 ft coil is a Dayton D46 example; use your product’s length. Dobies with cast-in wire may need no separate tie-wire allowance. Welded mesh crossings are not counted as hand ties.

      Dobies & chairs

      Enter support spacing from the placement plan/product. Counts use a full rectangular support grid at the reinforcement extents, including boundary rows. Dobies support the bottom mat; chairs count once per gap between mats. Height, bearing surface and support capacity must suit your specified reinforcement—no height is selected here.

      Symbols identify quantities, not bearing locations. The estimating grid is not a support placement drawing.

      Additional bars from plans

      Separate project totals for diagonals, perimeter or trim bars. Counts include all slabs and mats; they are not multiplied automatically. Enter supplied cut lengths for bent bars, including hooks. These schedules do not draw bar locations or add supports.

        Cut / panel list
        Save your list

        From the plans to a reinforcement list

        This estimates straight, rectangular slab grids. Enter the specified spacing and clear edge cover, select the bar size and mat count, then set the stock and accessory details. It does not design reinforcement, anchorage, lap lengths, openings, bending, construction joints or support adequacy.

        How the counts work

        Each bar direction includes bars at both edge-cover limits. Bar centres sit half a bar diameter beyond the clear side cover. The count rounds up the number of spaces, so the distributed spacing does not exceed your input. Straight cut length is the slab dimension minus both end covers.

        Runs longer than stock are split using your lap. Full lengths and remainder cuts are packed into stock using a first-fit decreasing estimate, with cutting loss excluded. The allowance is applied to whole stock orders, mesh units, wire length and supports; it does not change the reinforcement grid. Verify the cutting schedule before ordering.

        Dobies, chairs and tie wire

        Dobies hold the bottom reinforcement off the bearing surface. Chairs between mats are counted separately for each mat gap. Both use your support-grid spacing, not an assumed universal spacing. No support height or safe load is inferred.

        Tie-wire length comes from your planned tie count and wire length per tie. Bar crossings, specified splice ties and loose-wire support ties are separate. Welded-wire mesh only uses the mesh-lap tie count you enter; it does not treat every welded crossing as a hand tie.

        Diagonal and supplementary bars

        Diagonal reinforcement can appear at internal corners, openings or other plan details. This tool does not infer a requirement from slab size. Use the additional-bar schedules to count the specified sizes and lengths separately from the grid; it does not design corner reinforcement or anchorage.

        Wire mesh sheets or rolls

        Supply the actual product dimensions and overlap. Flat sheets follow the selected orientation; “Either” compares rotations only when the plans allow it. They do not reuse offcuts. Rolls follow the selected strip direction and pack straight length cuts; width offcuts are not reused. Confirm grade and lap orientation with the reinforcement plan.

        Sources and assumptions

        Stock 20 ft, #4, one mat, 100% crossing ties and 10% purchase extra are editable example choices, not engineering specifications. Cover, spacing, wire per tie, mesh sizes/overlaps and support spacing start blank so you can supply the planned values.

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