BC BuilderCalc

construction

Rebar Calculator

Estimate rebar sticks for a rectangular reinforcement grid. Results update instantly as you change the inputs.

Start estimate Read FAQs
Output
yards / bags / cost
Mode
planning estimate
Rebar Calculator estimating scene A construction estimating worksheet with concrete forms, bag count notes, a tape measure, and supplier order math. ORDER 2.61 yd3 80 lb live order math waste + rounding
live order math 2.61 yd3

Enter non-negative dimensions. Product-specific fields use safe minimums where zero would make the calculation invalid.

Use product labels and local requirements for final ordering.

20 ft rebar sticks8120.00 square feet
Waste / coverage
24 in grid spacing
Area
120.00 ft²

Last reviewed: May 12, 2026 by the BuilderCalc editorial team.

Reinforcement planning

Rebar Calculator planning notes

Rebar estimates depend on grid spacing, edge clearance, lap requirements, and stock length. Use the calculator as a planning count, then verify the final layout.

Edge clearance affects count

Rebar should not run directly to the form edge. Clearance and cover requirements reduce the usable grid dimension.

Lap and waste are separate

Long runs may need overlapping bars. Add lap length and cutting waste after the base grid count.

How to use it

Keep the estimate tied to field measurements

01

Set grid dimensions

Use the reinforced area after accounting for edge clearance and concrete cover.

02

Choose spacing

Enter spacing in each direction based on the project design, not only a generic rule of thumb.

03

Account for laps

Long runs may need overlapping bars and cutting waste after the base count is known.

Related calculators

Try the slab calculator Calculate concrete yards and bags for garage slabs, shed bases, pads, and flatwork. Need sidewalk concrete? Calculate concrete for sidewalks, walkways, and narrow slab pours. Estimating a driveway? Estimate ready-mix concrete and bag counts for a residential driveway slab.
Check footing volume Estimate concrete yards and bags for continuous strip footings. Estimate wall concrete Estimate concrete yards for wall pours using length, height, and thickness. Calculate stair concrete Estimate concrete for solid stair pours using width, tread depth, riser height, and step count. Round columns and piers Calculate concrete volume for round columns and piers.
Need bag counts instead? Convert slab dimensions into 40 lb, 60 lb, and 80 lb concrete bag counts. Convert to cubic yards Calculate cubic yards of concrete from project dimensions. Work in cubic feet Calculate concrete cubic feet, cubic yards, and cubic meters.

FAQ

Concrete estimating questions

How do I estimate rebar for a slab?

Estimate bars in each direction based on slab dimensions, edge clearance, and spacing. Then account for stock length, laps, and waste.

What rebar spacing should I use?

Common slab grids may use 12, 16, or 18 inch spacing, but spacing depends on slab design, loads, and local requirements.

Does the calculator include lap splices?

Use the result as a planning count. Long runs may need lap length added based on bar size and project requirements.

Can wire mesh replace rebar?

Sometimes, but reinforcement choice depends on slab use, thickness, cracking control, loads, and local practice.