The calculation, without hidden assumptions
A slab rebar takeoff starts by counting parallel bar lines in each direction, not by dividing slab area by spacing. MAXScanner uses clear slab dimensions, edge cover and center-to-center spacing to count those lines, totals the run length in both directions, then applies an editable lap/waste allowance. Stock length, weight per foot and price are separate purchasing inputs so the page does not pretend a bar size or splice detail is universal.
How to use this calculator
Enter slab length and width, then the edge cover and center-to-center grid spacing taken from the actual reinforcement plan.
Check the returned line count in each direction and the raw bar length before any lap or waste allowance.
Enter the stock-bar length and, if useful, an actual weight-per-foot and price-per-stock-bar value for delivery and budget planning.
Where people use it
- •Material takeoffs for a specified slab grid
- •Comparing stock lengths for a known reinforcement layout
- •Estimating delivery weight after bar size has already been selected
Example: 20 × 12 ft slab at 12 in spacing
With a specified edge cover, the calculator finds how many bar centerlines fit across the clear width and clear length. Each set then runs in the opposite slab direction; those two totals are added before the lap/waste factor and stock-length rounding.
What the result does not assume
- •This is a quantity calculator, not reinforcement design. It does not select bar size, spacing, cover, development length, splice length or code compliance. Those values must come from the design or applicable requirements.
- •A percentage allowance is only a purchasing shortcut. Real splice locations and lap lengths depend on the reinforcement detail and may require a bar-by-bar schedule.
Frequently asked questions
Does this calculator recommend rebar spacing?+
No. Spacing is an input from the project design. The calculator only counts and totals bars after you enter the specified spacing.
Why include edge cover?+
The first and last bar centerlines usually do not sit at the slab edge. Entering the planned edge offset gives a more realistic count across the usable width and length.
Can it estimate rebar weight?+
Yes, if you enter the weight per foot for the bar actually being used. The calculator deliberately does not choose a bar size for you.
Semantic next steps
Continue the calculation
These links move to a different input, formula or project stage rather than a keyword variation of this page.
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MAXScanner keeps the formula and assumptions beside the result so you can verify the number before using it in a drawing, estimate, specification, worksheet or document. Where a supplier, manufacturer, drawing or applicable standard owns a requirement, that source remains authoritative.