Rex says
Everyday utility math — the kind you'd otherwise pull up four browser tabs for. I keep it to one clean answer.
Try a scenario
Click to load — tweak from there.Inputs
Result
Stock bars to buy
22
Total linear feet (incl. laps)
423
Estimated cost
$318
Bars running lengthwise
10
Bars running widthwise
16
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One click, a permanent link with your numbers baked in.
How to use this
- 1Enter slab length (ft).
- 2Enter slab width (ft).
- 3Enter grid spacing (in).
- 4Enter stock bar length (ft).
- 5Enter price per foot ($).
- 6Read your stock bars to buy on the right — it updates as you type.
- 7Hit Share to keep the scenario or send it to someone.
About this calculator
Counts the bars in a two-way grid at your spacing, adds lap splices, and prices the order. Grid spacing is usually 12 to 18 inches on centre for residential slabs.
Worked example
Using the values the calculator loads with:
Inputs
- Slab length: 20 ft
- Slab width: 12 ft
- Grid spacing: 16 in
- Stock bar length: 20 ft
- Price per foot: 0.75 $
Results
- Stock bars to buy: 22
- Total linear feet (incl. laps): 423.36
- Estimated cost: $317.52
- Bars running lengthwise: 10
- Bars running widthwise: 16
What each field means
Inputs
- Slab length (ft)
- The slab length used in the calculation, measured in ft. Starts at 20 ft so you have a working example on load.
- Slab width (ft)
- The slab width used in the calculation, measured in ft. Starts at 12 ft so you have a working example on load.
- Grid spacing (in)
- The grid spacing used in the calculation, measured in in. Starts at 16 in so you have a working example on load.
- Stock bar length (ft)
- The stock bar length used in the calculation, measured in ft. Starts at 20 ft so you have a working example on load.
- Price per foot ($)
- The price per foot used in the calculation, measured in $. Starts at 0.75 $ so you have a working example on load.
Results
- Stock bars to buy
- Returned as a whole number and shown as the headline result. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Total linear feet (incl. laps)
- Returned as a whole number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Estimated cost
- Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Bars running lengthwise
- Returned as a whole number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Bars running widthwise
- Returned as a whole number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
FAQ
How does the rebar calculator work?
Counts the bars in a two-way grid at your spacing, adds lap splices, and prices the order. Grid spacing is usually 12 to 18 inches on centre for residential slabs. The underlying maths is: Bars per direction = (Span ÷ Spacing) + 1, with lap length added per splice.
What do I need to enter?
5 values: slab length, slab width, grid spacing, stock bar length, and price per foot. Each field starts with a sensible default, so you can change one number at a time and watch the result move.
What does the stock bars to buy result mean?
It is returned as a whole number and updates live as you edit the inputs, so you can compare two or three versions of a scenario in a few seconds.
Is this calculator free, and do I need an account?
Yes, it's free, and no account is required. Nothing you type is stored on our servers — the maths runs entirely in your browser.
How accurate is the result?
It applies the standard formula exactly, so the arithmetic is precise. Estimates assume standard, average conditions — local rules, pricing, and materials vary.
Who is this tool for?
It's built for anyone doing everyday planning maths — a quick estimate that would otherwise need four browser tabs and a calculator app.
Accuracy and limitations
- Estimates assume standard, average conditions — local rules, pricing, and materials vary.
- Results are rounded for readability; add a buffer before ordering, booking, or committing.
- Double-check anything with a real cost attached against a local quote.
Related tools
Cite this calculator
Writing about this topic? Grab a citation — every link helps keep these tools free.
RevenueLab. (2026). Rebar Calculator. Retrieved from https://www.revenuelab.fyi/toolbox/rebar
<p>Source: <a href="https://www.revenuelab.fyi/toolbox/rebar" target="_blank" rel="noopener">Rebar Calculator — RevenueLab</a> (2026).</p>
Source: [Rebar Calculator — RevenueLab](https://www.revenuelab.fyi/toolbox/rebar) (2026).