Estimate reinforcement quantity, total steel length, steel weight, and rebar material requirements using contractor-grade rebar takeoff formulas.
For a slab grid, bars each way = span ÷ spacing + 1 (rounded up). Multiply bars × bar length for both directions, then multiply total feet by the bar's lb/ft for weight. Add laps and waste last.
Example: 20 × 20 ft slab, #4 at 12 in on center: 21 bars × 20 ft × 2 directions = 840 ft × 0.668 = 561 lb before laps and waste.
Slab takeoff — 24×24 ft · 6 in · #4 @ 12 in OC · 1 layer
| Rebar Size | Total Bar Runs | Total Length | Est. Weight | Waste | Ordering |
|---|---|---|---|---|---|
| — | — | — | — | — | — |
24×24 ft, #4 @ 12 in.
20×40 ft, #4 @ 12 in.
40×30 ft, #5, 2 layers.
50×80 ft, #5, 2 layers.
This rebar estimating calculator builds a two-way grid takeoff for bid-ready steel takeoff numbers. Cross-check spacing with the rebar spacing calculator and mesh layout on the rebar grid calculator.
One continuous bar in one direction across the effective span. Total runs equals bars each way times layers.
Commercial orders often use tons; retail yards may price per stick. This tool shows both.
Wall preset uses face length and height as the grid footprint—verify vertical vs horizontal bar schedules on your detail.
How we built this calculator: results use the standard volume, area, and coverage formulas shown on this page, with typical U.S. material densities, bag yields, and waste factors that you can override. Written and checked by the YardsCalculator editorial team. Last reviewed: October 2026.
Last updated: October 17, 2026