Free Concrete Slab Reinforcing Mesh & Rebar Calculator
Calculate rebar grid linear feet, standard 20ft stick counts, welded wire mesh coverage, rebar chairs, and total steel weight for concrete slabs.
🏗️ Slab Dimensions & Steel Style
📊 Material Takeoff & Quantities
Recommended Tools & Equipment
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Frequently Asked Questions
What size rebar is best for a residential driveway or garage slab?
#4 rebar (1/2-inch diameter) spaced at 16 or 18 inches on-center is the standard specification for residential concrete driveways and garage floors designed for passenger vehicles and light trucks.
How much overlap is required when splicing rebar?
The American Concrete Institute (ACI) recommends a minimum lap splice length of 30 to 40 bar diameters, or a minimum of 12 inches. For #4 rebar (1/2" dia), 15 to 18 inches of overlap tied with 16-gauge tie wire is standard.
Where vertically should rebar sit in a 4-inch concrete slab?
Rebar should sit in the upper third to middle of the slab (between 1.5 and 2.5 inches below the top finished surface) with a minimum of 1.5 to 2 inches of concrete cover over the steel to protect it from moisture infiltration and corrosion.
How many rebar chairs do I need per square foot?
Rebar chairs should be placed on a 2.5-foot to 3-foot grid pattern, which works out to approximately 1 chair for every 6 to 9 square feet of slab area. Perimeter bars and lap splices require additional support to prevent sagging.