Rebar calculator
Count one two-direction mat with bars at both edge lines.
Formula
nL = ceil((W−2c−d)/s)+1; nW = ceil((L−2c−d)/s)+1; total = nL(L−2c)+nW(W−2c)
Slab length: 12 ft · Slab width: 10 ft · Clear cover: 2 in · Bar diameter: 0.5 in · Maximum center-to-center spacing: 12 in · Bars along length ≈ ceil(max(0,((10 ft × 0.3048 m/ft)-2×(2 in × 0.0254 m/in)-(0.5 in × 0.0254 m/in)-(8.881784197 × 10⁻¹⁶)×((10 ft × 0.3048 m/ft)+2×(2 in × 0.0254 m/in)+(0.5 in × 0.0254 m/in)))÷(12 in × 0.0254 m/in)))+1 · Bars along width ≈ ceil(max(0,((12 ft × 0.3048 m/ft)-2×(2 in × 0.0254 m/in)-(0.5 in × 0.0254 m/in)-(8.881784197 × 10⁻¹⁶)×((12 ft × 0.3048 m/ft)+2×(2 in × 0.0254 m/in)+(0.5 in × 0.0254 m/in)))÷(12 in × 0.0254 m/in)))+1 · Total cut length ≈ (11)×((12 ft × 0.3048 m/ft)-2×(2 in × 0.0254 m/in))+(13)×((10 ft × 0.3048 m/ft)-2×(2 in × 0.0254 m/in))+0×(0.5404627647)
How to use
- Enter slab dimensions and clear cover.
- Enter bar diameter and design spacing.
- Read bars in both directions and total cut length.
Examples
- 2 × 1 m, cover 5 cm, bars 2 cm, spacing 20 cm: 6 + 11 bars, 21.3 m.
Frequently asked questions
What does cover mean?
Clear concrete cover to the steel surface; the outer bar center is cover plus half a diameter.
Does this choose reinforcement?
No. Use the design values. Bars are equally spaced between edge centers; overlapping bars or impossible spans are rejected.
Are laps and hooks included?
No. This is one straight mat, without laps, hooks, waste or stock-bar cutting optimization.
Sources
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