🔩 Rebar Calculator

Calculate the reinforcement bars needed for a slab — enter the slab size, bar spacing and diameter to get total bar count, length and weight.

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    Frequently Asked Questions

    How is rebar spacing chosen for a slab?

    Spacing depends on slab thickness, span and structural load — 8–12 inches on centre is common for residential slabs, but always follow your structural engineer's drawing.

    Does this include lap splices?

    No — this gives the base grid length only. Add roughly 40–50 bar diameters of extra length per splice if your bars don't run in single continuous lengths.

    What's the difference between this and the Steel Weight Calculator?

    This tool is specifically for a two-way slab reinforcement grid based on spacing; the Steel Weight Calculator is a general-purpose tool for any list of bar sizes and lengths.