How to find weight of 8mm,10mm,12mm, 16mm, 20mm, 25mm, 32mm steel bars?

How to find weight per unit length of different dia HYSD bars:- 

Formula :- (d×d)/162.2 OR d^2/162.2

Generally length of steel bar is 12mtr

We are calculate weight for 1mtr length of bar :-

(1):- 8mm dia :- 8×8/162.2 = 0.314 kg/mtr
(2):- 10mm dia :- 10×10/162.2 = 0.616 kg/mtr
(3):- 12mm dia :- 12×12/162.2 = .887 kg/mtr


Like that 16mm = 1.578 kg/mtr
                 20mm = 2.466 kg/mtr
                 25mm = 3.853kg/mtr
                 32mm = 6.313 kg/mtr