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Rebar Calculator

Calculate total rebar length, grid stick counts, weight, and tie wire for concrete slabs.

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Input Parameters

Enter details for calculation.

20ft Rebar Sticks

28 sticks
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Expert Tip

Standard rebar comes in 20-foot sticks. #4 rebar (1/2" dia) weighs 0.668 lbs per foot.

Calculation Methodology & Details

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Formula

Sticks = Ceil( (Rows × Length + Cols × Width) × 1.10 / 20 )

Applies standard construction engineering calculation formulas.

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Important Disclaimer

The calculations provided are for educational and structural planning purposes. Always consult a qualified general contractor or structural engineer for site-specific verification.

How to Calculate Step-by-Step

Follow these steps to complete the calculation:

1

Step 1

Enter slab length, width, and edge clearance.

2

Step 2

Set rebar grid spacing (typically 12" to 24" on center).

3

Step 3

Calculate total linear feet and number of 20-foot rebar sticks required.

Detailed Insights & Expert Guide

ℹ️ About this Calculation

Computes rebar grid reinforcement material for concrete foundations, driveways, footings, and retaining walls including overlap splice allowances.

Variable Glossary

Input

Grid Dimensions

Slab length, width, and center-to-center bar spacing in inches.

Parameter

Rebar Size (#)

Standard rebar diameter designation (#3 = 3/8", #4 = 1/2", #5 = 5/8").

FAQ

How far apart should rebar be placed in a driveway slab?
Driveway rebar grid spacing is typically 18 to 24 inches on center using #4 (1/2") rebar.
How much lap splice is required when connecting rebar?
Code requires a minimum lap splice of 30 to 40 bar diameters (approx. 15 to 20 inches for #4 rebar).
What does rebar size number mean?
Rebar size number represents eighths of an inch (#3 = 3/8", #4 = 4/8" or 1/2", #5 = 5/8").