Rebar Calculator
Estimate a simple rectangular reinforcement grid from slab dimensions, bar spacing and stock bar length. The calculation is for material estimating only.
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How the rebar calculator works
Estimate a simple rectangular reinforcement grid from slab dimensions, bar spacing and stock bar length. The calculation is for material estimating only.
Bars across a dimension are based on ceiling((dimension ÷ spacing) + 1). Total stock pieces are based on the total bar length divided by stock bar length. The calculator is designed to give a useful first-pass material estimate while keeping the assumptions visible. For a purchase, compare the result with the product packaging or supplier quotation.
Common search terms for this tool include rebar calculator, rebar spacing calculator, reinforcement bar calculator, rebar quantity calculator. The wording is included naturally so the page answers the same questions people ask when planning a project.
Frequently asked questions
Does this design structural reinforcement?
No. Bar size, spacing, cover, laps and placement should come from structural plans or applicable code.
Why is bar count rounded up?
You need complete bar positions at the edges of the grid.
Does it account for laps?
No. Add lap and splice requirements from your project plans.
Can I estimate stock length?
Yes. Enter the length of bars available from your supplier.