Enter slab dimensions, bar spacing, and bar size to get bar count in each direction, total linear feet with lap allowance, weight, stick count, tie quantity, and an installed cost range.
Every result is a planning estimate, not a quote or an engineering determination. Real pricing depends on soil conditions, access, existing structure, engineering requirements, and your jurisdiction’s current fee schedule. For structural questions we coordinate with a licensed engineer — we do not perform engineering ourselves. Get a site-specific estimate before committing to a budget.
Bars in each direction are laid out across the opposite dimension. Running bars the length of a 30 by 20 ft slab means spacing them across the 20 ft width: take the width in inches, subtract cover from both edges, divide by the spacing, and add one for the bar that starts the run. Do the same in the other direction and you have the grid. Multiply each count by the length of those bars, add them together, and you have linear feet before splices.
Then add for laps. Rebar arrives in 20 ft sticks, so any slab dimension over 20 ft requires splices, and a splice is not a butt joint — the bars overlap so the load transfers through the concrete between them. Ten percent covers a normal residential grid. Heavily spliced layouts or short stock can push it higher.
The $0.85 to $1.60 per linear foot range is installed cost in the Bay Area: material, chairs, tie wire, and the labor to lay out, cut, bend, tie, and support the grid. Material alone is roughly a third of that. Ordering a few extra sticks is cheap insurance — a delivery on pour day to cover a shortfall costs far more than the steel.
We place reinforcement on every slab we pour. See new home foundations or concrete flatwork and driveways.
Common residential slabs use #4 bar at 16 or 18 inches on center each way, but the correct answer is whatever your structural drawings specify. Spacing depends on slab thickness, soil bearing, expansive clay, and the loads above. Use this calculator to price and order the grid your engineer already designed.
Welded wire mesh controls shrinkage cracking in light-duty flatwork and costs less. It does not provide the structural capacity of a rebar grid, and it is notoriously hard to keep at the right height during a pour. For driveways carrying heavy vehicles, expansive soils, or anything structural, rebar is the right call.
Rebar comes in 20 foot sticks. Any run longer than that needs a splice, and splices overlap rather than butt together, so every joint consumes extra bar. Ten percent covers a typical residential grid. If your slab has many short runs or the yard sends 10 foot stock, order more.
No. Standard practice is tying every intersection around the perimeter and roughly every second or third intersection in the field, which is enough to keep the mat from shifting during placement. The tie count shown here is the total number of intersections, so treat it as the maximum.
Tell us what you're building — a new home, an ADU, an addition — and we'll get back to you with next steps, usually within one business day.
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