Rebar Calculator

Use it when your task matches one of these common needs: Estimate stock rebar bars for a simple rectangular slab grid. Compare 12-inch, 18-inch, and 24-inch spacing. It works best when you already know the measurements, amounts, units, or options the page asks for.

In plain language: Lengthwise bars = floor(slab width x 12 / spacing inches) + 1. Widthwise bars = floor(slab length x 12 / spacing inches) + 1. Total linear feet = lengthwise bars x slab length + widthwise bars x slab width. Add waste, divide by stock bar length, and round up. The examples on the page are there so you can compare your inputs with a worked example before copying the answer.

Slab length and width: the rectangular slab dimensions for the grid estimate. Bar spacing: the distance between parallel bars; smaller spacing means more bars. Stock bar length: the length of one purchased bar from the supplier. Waste percent: extra length for cuts, lap planning, and small layout changes.

Read the headline estimate first, then check the material, waste, coverage, and unit lines. For project tools, the supporting lines are often the difference between a rough idea and a list you can actually shop from.

This is a material takeoff, not structural design. Bar size, spacing, laps, cover, supports, edge distance, and code requirements need professional review. Also check the unit, scale, mode, and result limit because small input changes can change the answer.

It counts a simple two-direction grid for a rectangular slab. It returns bars running each direction, adjusted linear feet, and whole stock bars to buy.

Yes, it is aimed at simple rectangular slab takeoffs. Enter slab length, slab width, bar spacing, stock bar length, and waste percent.

Not on this page. This page estimates grid length and bars to buy. Use the Rebar Weight Calculator if you need pounds or tons from bar size and quantity.

Only as a rough material-count idea. Walls, footings, beams, and structural slabs can need different bar sizes, layers, bends, hooks, spacing, cover, and lap details.

Spacing is the distance between parallel bars. If the bars are closer together, more bars fit across the slab, so total linear feet and stock bars go up.

Only if you cover them with the waste percent. Real lap length depends on bar size, concrete strength, bar spacing, cover, grade, and the project drawings.

No. It is for estimating materials before ordering or comparing layouts. The actual reinforcement design should come from the plan, code requirements, or a qualified professional.

Check the drawing, required bar size, spacing, slab thickness, cover, chair/support needs, lap length, stock lengths, delivery minimums, and local code rules.

No. The calculator runs in your browser tab. Your recent answers stay only on the page while you use it, and they are not sent to a server.