Rebar Quantity Calculator | Free Construction Calculators

Calculate the amount of rebar needed for concrete slab reinforcement.

feet
feet
inches
inches

Rebar Spacing Guidelines

  • 12 inches: Heavy-duty slabs, commercial, driveways
  • 18 inches: Standard residential slabs (most common)
  • 24 inches: Light-duty slabs, patios

Common Rebar Sizes

  • #3 (3/8"): Light residential, patios
  • #4 (1/2"): Most residential slabs (most common)
  • #5 (5/8"): Heavy residential, light commercial
  • #6 (3/4"): Commercial applications

Lap/Overlap Requirements

Rebar should overlap at splices. Typical lap length is 12-18 inches for #4 rebar. Larger bars require longer laps. Consult local building codes.