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Rebar Calculator

Estimate rebar quantity, length, weight & material list for slabs, walls & footings

Inputs

ft
ft
in
in
in
$ / bar

Results

Formulas Used

Grid Length = Length − 2 × Edge Clearance
Grid Width = Width − 2 × Edge Clearance
Bars (Dir 1) = ⌊ Grid Width / Spacing ⌋ + 1
Bars (Dir 2) = ⌊ Grid Length / Spacing ⌋ + 1
Total Length = Σ(Bars × Bar Length) + Lap Allowance
Lap Allowance = Lap Length × (Pieces per Bar − 1) × Bars (when bar > standard length)
Weight (lb/ft) = (π × d² × 490) / 576   d = diameter in inches, 490 = steel density (lb/ft³)
Total Weight = Total Length × Unit Weight
Pieces = Σ⌈ Bar Length / Standard Bar Length ⌉ × Bars

Lap length defaults to 40 × bar diameter (common practice). Override with your own value if needed. Results are for material estimation only. Always follow your project's engineering specifications.