Weight of steel bars= Cross sectional area of steel bar x Length of steel bar x Density of steel bar.
That means,
W = A x L x ρ
Where,
A = Area = πD²/4
π (pi) = 3.14
D = Diameter of steel bar in millimeter
L = Length of steel bar in meter
ρ (Rho) = Density of steel bar = 7850 kg/m³
Therefore,
W = 3.14 x D²/4 x L x 7850
But there are two conflicting unit in the formula. Those are millimeter for D and m for ρ (Rho).
We have to convert either D or ρ to same unit.
Let’s convert D from millimeter to meter.
1 millimeter = 1/1000 meter
Lets implement this to the formula,
W= 3.14 x D²/(4x1000x1000) x L x 7850
= D²L/162
Using this formula we can calculate the weight of steel bars.
Example
How to calculate the weight of 100 meter long 16mm ø bar?
In this example,
D= 16mm
L = 100 m
So,
W = D²L/162
= 16² x 100/162
= 158 kg (approx)
Note: W = D²L/162 IS ONLY FOR ROUND BAR…