# How to Calculate Weight of Steel Bars?

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.

## Unit Weight of Steel Flat Bars

The density of mild steel is 7850kg/m3. 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

## Unit Weight of Steel Rods

Here, the density of steel is taken as 7850kg/m3. 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/m3

= (3.14 x (D2 /4) x L) x 7850kg/m3

= (D2 x 6162.25L)/1000000

= D2 L x 0.006162 = D2 L / 162.28

Weight of Steel Bar  = [ D2 L / 162.28] in Kg and Length ‘L’ in m

Weight of Steel Bar = [ D2 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  = [D2 L / 162.28]

Hence, the weight of :

1. 10mm dia bar = (10x10x1)/162.28 = 0.616kg
2. 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.