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Grid bars, lap splices, 20 ft sticks, steel weight and the delivered cost.
Common US slabs at 18 in spacing with #4 bar and a 6 in edge allowance.
Tap a preset in the calculator above to load a typical job, then adjust the numbers to match your site.
Starting points: Patio 12 × 12 ft · Driveway 20 × 24 ft · Garage 24 × 24 ft · Shed 10 × 12 ft · RV pad 12 × 40 ft
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Measure the slab, pick the spacing from your engineer or code, then order sticks with laps and waste.
At 18 in spacing you need about 34 bars and roughly 833 linear feet with laps and a 6 in edge allowance, which is 42 twenty-foot sticks of #4 bar.
About $0.30 to $0.60 per linear foot, or $6 to $12 per 20 ft stick, in 2026. A typical two-car slab needs $270 to $540 of steel.
Forty bar diameters: 20 in for #4, 25 in for #5, 30 in for #6. Tie the laps with wire so the bars do not move during the pour.
Rebar for driveways, footings and anything carrying vehicles. Mesh is enough for patios and walkways, and it costs about half as much per square foot.
About one chair or dobies every 3 to 4 ft in both directions, keeping the mat at mid-slab depth. Tie wire runs about 1 lb per 10 bars.
No. Concrete shrinks and cracks; rebar holds the pieces together and carries load across a crack. Control joints decide where cracks appear.
Using the calculator defaults, patio 12 × 12 ft gives Bars in the grid: 18 and Steel cost: $118, with a typical range $82 to $153. Change the waste allowance, material or thickness to match your site.
Using the calculator defaults, rv pad 12 × 40 ft gives Bars in the grid: 37 and Steel cost: $383, with a typical range $268 to $498. Change the waste allowance, material or thickness to match your site.