How Far Apart Should Rebar Be?

Rebar spacing guidance for slabs-on-grade. Learn typical spacing ranges, what affects spacing, and practical starting points.

Typical ranges

Common starting points are 12–24 inches on center depending on slab thickness and load class.

Slab thickness, load type, joint layout, and whether the slab is engineered change spacing.

Use the calculator and confirm for your conditions or specification.

Fast path: Use the slab thickness calculator for a coherent recommendation, then confirm rebar spacing and volume.