Rebar Grid Calculator

Last updated: 27 Nov 2025 | Author: Brij | Review By: Irshad

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A simple and accurate Rebar Grid Calculator that helps you estimate the number of rebars, total rebar length, and steel weight for any slab. Includes formulas, and a complete example for easy understanding.

Slab Length:

Slab Width:

Rebar Diameter:

Rebar Spacing (X-Direction):

Rebar Spacing (Y-Direction):

Rebar Grid Calculation Results

Number of Rebars in X-Direction:

bars

Number of Rebars in Y-Direction:

bars

Total Rebar Length:

Total Rebar Weight:

A rebar grid is used in slabs, pads, and foundations to distribute loads evenly and reduce cracking. A Rebar Grid Calculator helps you quickly find how many rebars you need in each direction and the total steel required for your slab. This blog explains the inputs, outputs, formulas, and a complete example so anyone can follow the calculation easily.

Formulas Used in the Rebar Grid Calculator

1. Number of Rebars in X-Direction

Rebars in the X-direction run along the width of the slab.

Formula

$N_x = \frac{Slab\ Width}{Spacing_x} + 1$

2. Number of Rebars in Y-Direction

Rebars in the Y-direction run along the length of the slab.

Formula

$N_y = \frac{Slab\ Length}{Spacing_y} + 1$

3. Total Rebar Length

Total steel length in the grid:

Formula

$Total\ Length = (N_x \times Slab\ Length) + (N_y \times Slab\ Width)$

4. Total Rebar Weight

Weight depends on rebar diameter.

Formula

$Weight = Total\ Length \times Unit\ Weight$

The unit weight of rebar is:

$Unit\ Weight = \frac{d^2}{162}$

(where d = rebar diameter in mm)

Example Calculation

Let’s assume:

Slab Length = 20 ft (6.10 m)
Slab Width = 10 ft (3.05 m)
Spacing in X direction = 6 in (0.152 m)
Spacing in Y direction = 8 in (0.203 m)
Rebar Diameter = 10 mm

1. Number of Rebars in X-Direction

$N_x = \frac{3.05}{0.152} + 1 = 20.06 \approx 21$

2. Number of Rebars in Y-Direction

$N_y = \frac{6.10}{0.203} + 1 = 31.04 \approx 32$

3. Total Rebar Length

$Total Length = (21 \times 6.10) + (32 \times 3.05)$

$Total Length = 128.1 + 97.6 = 225.7\ m$

4. Total Rebar Weight

Step 1: Unit weight

$Unit Weight = \frac{10^2}{162} = 0.617\ kg/m$

Step 2: Total weight

$Weight = 225.7 \times 0.617 = 139.3\ kg$

FAQs

1. What is a rebar grid in construction?

A rebar grid is a network of steel bars placed in two directions within a slab or foundation. It strengthens the concrete and prevents cracking caused by load, temperature changes, and settlement.

2. How do I calculate the number of rebars in a grid?

To calculate rebar count, divide the slab dimension by the spacing and add one.

For example:

Rebars in X-direction = (Slab Width ÷ Spacing X) + 1
Rebars in Y-direction = (Slab Length ÷ Spacing Y) + 1

3. Does rebar diameter affect the number of rebars?

No. Rebar diameter does not change rebar quantity or spacing.

It only affects weight, because different diameters have different unit weights per meter.

4. What spacing is commonly used for rebar grids?

Typical spacing is 6 in, 8 in, or 10 in (or 150 mm / 200 mm), depending on the structural design. Smaller spacing gives more strength and reduces cracking.

5. How do I calculate the total weight of rebar?

Multiply the total rebar length by the unit weight of the chosen rebar size.

Unit weight formula:

$Unit\ Weight = \frac{d^2}{162}$

(where d = diameter in mm)

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Rebar Grid Calculator

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