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The total weight of steel bars can be determined by calculating the unit weight of each bar. This is calculated after the final estimation of total steel required for a construction project.

In this article, the calculation of the unit weight of steel flat bars and steel rods is explained with examples.

**Also Read:** Estimation of Steel Reinforcement for slab,beam and column

## Unit Weight of Steel Flat Bars

The density of mild steel is 7850kg/m^{3}. A mild steel flat bar is specified by its width and thickness in millimeters. If so, the weight of the steel bar is given by:

Weight of steel bar = Volume of steel Bar x Density of steel

**Weight of steel Flat bar = (Length x width x thickness) x 7850**

**Example 1: Determine the unit weight of MS Flat bar of width 40mm and Thickness of 20mm.**

**Weight of steel bar = Volume of steel Bar x Density of steel**

Weight of steel bar = (Length x width x thickness) x 7850

Unit Weight of steel bar = (1 x .040 x .020) x 7850

= 6.28kg/m

Also Read: Reinforcement Quantity Estimation

## Unit Weight of Steel Rods

Here, the density of steel is taken as 7850kg/m^{3}. A mild steel round bars are specified by their diameters in millimeters(mm). If so, the weight of the steel bar is given by:

Weight of steel bar = Volume of steel Bar x Density of steel

Weight of steel rod = (Cross sectional area of steel rod x Length) x 7850kg/m^{3 }

= (3.14 x (D^{2 }/4) x L) x 7850kg/m^{3 }

=
(D^{2} x 6162.25L)/1000000

= D^{2} L x 0.006162 = D^{2 }L / 162.28

**Weight of Steel Bar = [ D ^{2 }L / 162.28] **in Kg and Length ‘L’ in
m

**Weight of Steel Bar** = **[ D ^{2 }L / 533] **in Kg and Length ‘L’ in foot

To calculate the unit weight, length “L’ becomes unity.

**Example 2: Determine the unit weight of 10mm and 12mm diameter steel bars.**

The formula is :

**Weight of Steel Bar = [D ^{2 }L / 162.28]**

**Hence, the weight of** :

- 10mm dia bar = (10x10x1)/162.28 = 0.616kg
- 12mm dia bar = (12x12x1)/162.28 = 0.8874kg

There is no exact method to calculate the weight of steel. Determination of weight based on the cross-sectional area as explained above does not give accurate results. It is mostly recommended to follow the manufacturer’s unit-weight chart in order to calculate the weight of the steel bars.