Rebar Calculator (Grid Pattern)

Enter your slab dimensions, rebar spacing and standard bar length to estimate the rebar needed for a two-way grid.

Rebar Calculator (Grid Pattern)

Estimate the number and total length of rebar needed for a two-way grid pattern in a concrete slab.

This calculator provides a material estimate for general planning purposes only. Always add a safety margin and confirm quantities with your supplier or contractor before purchasing, since real-world waste, layout and offcuts vary by project.

For a standard two-way rebar grid, this calculator counts the bars needed in each direction based on your spacing, then converts the total linear footage into the number of standard-length bars to purchase.

Example

  • With the default values shown above, this calculator returns: Bars Running Lengthwise ≈ 11.00; Bars Running Widthwise ≈ 21.00; Total Linear Feet of Rebar ≈ 430.00; Standard Bars to Buy ≈ 22.

Frequently Asked Questions

How is this calculated?

The calculator finds how many rebar lines run in each direction based on your spacing, multiplies each set by the slab's other dimension to get total linear feet, then divides by your standard bar length (rounding up) to find how many bars to buy.

What rebar spacing is typical?

12 to 18 inches on-center is common for residential slabs, but requirements vary by slab thickness, load and local building code — check your project's engineering specification.

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