Steel Rebar Calculator
Use this steel rebar calculator to estimate a simple two-direction reinforcement grid for a rectangular slab. Enter slab dimensions, rebar spacing, stock bar length and weight per foot to estimate total linear footage, stock pieces and approximate steel weight.
Enter project details
Planning estimate only. Confirm local prices, supplier specifications and site conditions before ordering.
Your estimate
This estimates quantity only. Bar size, spacing, laps, cover and reinforcement design must follow approved plans and applicable code requirements.
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How the steel rebar calculator works
Bars in each direction are based on slab dimensions and center-to-center spacing. Total linear feet equals the combined length of both bar directions, with waste applied before stock pieces and weight are estimated.
For a better estimate
- Structural reinforcement must follow approved plans, code requirements and engineering guidance.
- Account for required concrete cover and lap lengths rather than placing steel directly at slab edges.
- This calculator is for quantity planning only and does not design reinforcement size or spacing.
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Frequently asked questions
How do I calculate rebar quantity?+
Estimate the number of parallel bars from spacing in each direction, multiply each count by its run length, then add lap and waste allowance.
What rebar spacing should I use?+
Spacing is a design decision and depends on slab thickness, loads, soil and local requirements. Use the spacing specified by the project design.
Does this calculator include rebar laps and waste?+
Yes, through the adjustable allowance, but actual lap lengths and detailing must follow the approved reinforcement plan.