Rebar Calculator

Enter the length and width of your concrete slab in feet. For irregular shapes, calculate rebar for each rectangular section separately and add the totals.

Choose the appropriate bar size based on slab thickness and load requirements. #4 (1/2 inch) is standard for most residential slabs. The calculator shows weight per foot for each size.

Standard spacing is 12 inches on center in both directions. Use 6 inches for heavy loads (driveways, equipment pads) or 18 inches for lighter applications. Spacing can be set independently for each direction.

The default 10% waste factor accounts for cuts, overlaps, and unusable pieces. Increase to 15% for complex shapes or if bars must be cut from standard 20-foot lengths.

The calculator shows bars needed in each direction, individual bar lengths, total linear feet, and total weight. Use linear feet for ordering cut-to-length rebar, or weight for bulk purchases.