Rebar material calculator

Count straight bars in two directions with edge bars and a maximum spacing.

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Slab length

Slab width

More inputs and assumptions

Maximum spacing

Edge inset

Answer

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Count straight bars in two directions with edge bars and a maximum spacing.

More results

Precision and calculation record

Decimal places in numeric results and text downloads

Rounding changes displayed numbers, not the calculation. Text, fractions, matrices and CSV schedules keep their own formatting. Automatic keeps up to 12 significant digits, with money shown to cents where applicable.

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Formula and assumptions

Each direction uses ceiling(clear width/spacing) + 1 bars. Equal spacing is no greater than your input. No hooks, laps, wastage, stock cutting, diameter or structural design is included.

Automatic precision shows numbers to 12 significant digits. Thousands separators such as 1,000 are accepted; use a dot for decimals.

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Updated 2026-09-26

Using Rebar material calculator

Count straight bars in two directions with edge bars and a maximum spacing.

Each direction uses ceiling(clear width/spacing) + 1 bars. Equal spacing is no greater than your input. No hooks, laps, wastage, stock cutting, diameter or structural design is included.

Next: Rebar weight calculator

A worked example

Example inputs: slab length = 10, slab width = 6, maximum spacing = 0.5, edge inset = 0.1. Bars in both directions = 34.

Before you use the result

Each direction uses ceiling(clear width/spacing) + 1 bars. Equal spacing is no greater than your input. No hooks, laps, wastage, stock cutting, diameter or structural design is included.

Example results for slab length

These examples use Slab width: 6; Maximum spacing: 0.5; Edge inset: 0.1. They are reference calculations, not recommended settings.

Slab length	Bars in both directions
5	24
10	34
20	54

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