Calculate concrete slab grid and footing rebar linear footage, 20-ft stock bar sticks, total tonnage, lap splices, and support chairs across #3 through #8 bar sizes.
The rebar take-off calculates effective dimensions after edge setbacks, adds contact lap splices (\(40 \times d_b\)), applies waste cut allowance, and divides by standard 20-foot stick lengths:
Concrete possesses high compressive strength but extremely low tensile strength (only 10% of compressive). Unreinforced concrete inevitably shrinks during hydration and thermal cycling, fracturing along stress lines without a bonded rebar grid.
Simply butting two rebar ends together transfers zero tensile load. ACI 318 structural code requires a contact lap splice of 40 bar diameters (20" for #4 rebar, 25" for #5 rebar). Omitting splice length calculations leads to ordering 15% to 25% too few bars.
Lumber yards and steel distributors sell rebar exclusively in rigid 20-foot straight lengths (or coiled #3/4). Our calculator rounds linear footage into exact purchasable 20-foot sticks with a realistic cutting scrap buffer.
Rebar left resting on gravel or mud subgrade provides virtually zero tensile reinforcement to the slab. Concrete chairs elevate the steel cage into the tension zone (middle to upper third), providing required 2" of concrete cover underneath.
Choose flat slab/driveway 2-way grid or continuous trench footing.
Input length, width, and concrete edge cover setback (2" to 3").
Select ASTM bar diameter (#3 up to #8; #4 is residential standard).
Configure on-center spacing (12" or 18") and 40d lap splice overlap.
Review 20-ft stock stick count, total steel tons, and chair supports.
| Bar Size Designation | Nominal Diameter | Weight per Foot | Weight per Meter | Standard Lap Splice (40d) | Common Applications |
|---|---|---|---|---|---|
| #3 Rebar (10M) | 0.375 in (9.52 mm) | 0.376 lbs/ft | 0.560 kg/m | 15 inches | Sidewalks, pool copings, column ties |
| #4 Rebar (13M) | 0.500 in (12.70 mm) | 0.668 lbs/ft | 0.994 kg/m | 20 inches | Residential slabs, driveways, garage floors |
| #5 Rebar (16M) | 0.625 in (15.88 mm) | 1.043 lbs/ft | 1.552 kg/m | 25 inches | Commercial slabs, heavy vehicle pads, footings |
| #6 Rebar (19M) | 0.750 in (19.05 mm) | 1.502 lbs/ft | 2.235 kg/m | 30 inches | Retaining walls, bridge decks, structural columns |
| #7 Rebar (22M) | 0.875 in (22.22 mm) | 2.044 lbs/ft | 3.042 kg/m | 35 inches | Heavy foundations, industrial mats, parking decks |
| #8 Rebar (25M) | 1.000 in (25.40 mm) | 2.670 lbs/ft | 3.973 kg/m | 40 inches | High-rise structures, deep caissons, heavy civil |
Pre-loaded bar diameters, cross-sectional areas, and certified linear weights per foot/meter.
Calculates longitudinal and transverse rebar stick counts for concrete foundation slabs and driveways.
Automatically adds 30d to 40d bar diameter overlap lengths at splices to ensure full tensile strength.
Converts total required rebar footage into standard commercial mill lengths with cutting waste buffers.
