Rebar Calculator
Estimate rebar bars, linear feet and weight for any slab.
Use this rebar calculator to estimate the number of bars, total linear feet, weight, and 20 ft sticks required for a slab based on its dimensions and bar spacing. The calculation treats the rebar as a grid, with bars running in both directions across the slab.
Linear feet
320
16 × 20 ft bars
Weight
214
lb (approx)
Tie wires
128
intersections
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Recommended tools & materials
Handy picks for this project on Amazon.
Quikrete Concrete Mix (80 lb)
Standard high-strength bagged mix
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Concrete Mixing Tub
Mix bags by hand without a mixer
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Magnesium Bull Float
Smooth and level fresh slabs
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Concrete Edger & Groover Set
Clean edges and control joints
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How does the rebar calculator work?
Rebar is placed in a grid. Bars run each direction at the chosen spacing. Total linear feet = (bars long × slab length) + (bars short × slab width). A standard rebar stick is 20 ft.
#4 bar weighs 0.668 lb/ft. Divide linear feet by 20 to get sticks to order.
What else do people ask about this calculator?
What spacing should rebar be in a slab?
16 in OC is typical for residential slabs. 12 in OC for heavier loads (driveways with trucks) and 24 in OC for light patios.
What size rebar for a driveway?
#4 (1/2 in) rebar in a 12–16 in grid is standard for residential driveways 4–6 in thick.
Which related calculators should I use next?
Where can I learn more about these materials?
Weights, coverage, types and buying tips for the materials this calculator estimates.
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Complete Your Concrete Project
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MARSHALLTOWN Magnesium Float
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Kraft Tool Concrete Edger
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Edward Tools Hand Mixer
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