Construction Cost Estimating


How to determine the weight of mild steel bar in MKS system

In this civil engineering article, you will learn how the formula W = D2/ 52.9 x L is derived for Mild Round Steel Bar weight calculation.

Assume the length of the bar as 20 feet and diameter of the bar as #4 i.e. 4/8 inches.

We know, 1 inch = 8 sooters
and 1 soter = 1/8 inch

The weight of the mild steel bar will be calculated as follow :-
W = D2 / 52.9 x L

Here, W denotes weight of mild steel bar in Kg, D denotes diameter or numbers of bar and L denotes length of the bar.

After putting all the values, we get the following result :-

W = 42/52.9 x 20 = 6.04 Kg

Now, Weight = volume x unit weight

or, W = X-sectional area x length x 222.32

For mild steel, unit weight is taken as 7850 kg/m3 or 222.32 kg/ft3

As steel bar is circular in section, W = πD2/4 x L x 222.32

To divide the unit weight of feet to sooter, divide it with 96 i.e. W = πD2/4 x 962 x L x 222.32
(1 feet = 96 sooter or 12 inch = 96 sooters)

W = 698.438 D2 x L / 36864

W = 0.01894634332 D2 x L

In friction form, it can be written as follow :-

W = 1/ 52.9, since 1/52.9 = 0.018946

or, 1 D2/52.9 x L
or, D2/52.9 x L

To learn the process in detail, go through the following video tutorial.

Video Source: SL Khan

How to determine the weight of mild steel bar in MKS system