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Rebar Calculator

Estimate reinforcing bar count, total length, intersections, and approximate weight for a slab grid.

Reviewed
2026-09-05
Units
US + metric

Calculated result / live

18 #4 bars

Order 191.4 ft of #4 rebar for 18 cut bars, with 10% length allowance.

#4 at 16.0 in OC, 2.0 in edge cover, 81 grid intersections. Bar weight uses the cited 0.668 lb/ft table value.

Input panel

Project measurements

Secondary quantities
Bars along length9
Bars along width9
Intersections81
Ordered length191.4 ft
Approximate weight127.9 lb

Calculation trace

Formula with your numbers

9 bars × 9.67 ft + 9 bars × 9.67 ft = 174.0 ft; + 10% = 191.4 ft

18 #4 bars
01

What this rebar calculator calculates

A 12 × 10 ft grid at 12 in OC with 2 in cover has 11 bars along one direction and 13 along the other. Cover changes both counts and cut length.

Formula

Bars = ceiling(usable dimension ÷ spacing) + 1; total length = bars in each direction × usable run; add waste and multiply by lb/ft.

Worked example

With #4 bar at 0.668 lb/ft, that grid has 254.0 ft before waste and weighs about 169.7 lb before tying wire and lap changes.

Ordering decision

Use the structural drawings for bar size, spacing, laps, chairs, and cover. This page is a material takeoff, not a reinforcement design.

The page cites the applicable Uzi Tools reference table beside the calculator. Product labels, current editions, local code, and a licensed professional govern structural, electrical, and life-safety work.

02

How to use it

  1. Enter the measured dimensions and keep the displayed units beside each field.
  2. Review the rebar grid length and weight result and the substituted formula before ordering.
  3. Adjust waste for the layout, cut pattern, product package, and site conditions.
  4. Copy or print the material list, then verify the cited product data and local requirements.
03

Rebar grid length and weight

This slab rebar calculator counts bars in both directions inside the edge cover, reports grid intersections, and converts ordered length to approximate weight using the selected bar table.

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Limits and professional review

Measurements, product yield, waste, moisture, and site conditions can change the order quantity. Local code and a licensed professional govern structural and electrical work.

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Data sources

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Related calculations

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Same-project tools

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Questions specific to this estimate