What is the formula for weight of steel rebar of 1m length, diameter= d?

Approximate EquationWeight of steel rebar of1m length= (d*d)/Diameter unit is mm in equation.Example:Weight of Bar Diameter = (*)/ =0. Kg/mWeight of Bar Diameter = (*)/ =0. Kg/mWeight of Bar Diameter = (*)/ =1. Kg/m

density of steel*3.14*dia*dia/4

Weight of Steel Bar/m = Density of Steel * Crosectional Area of Steel Bar=Density *(22/7)*d*d/4

Weight=d x d/ 162.196 kg/metre 

Weight of 1m steel bar(Kg) = d^2/162

Where d is diameter of the bar.

=Weight/Volume

W=*CrossArea(L)

where L=1meter          = Standard Steel Density

Therefore:  W=2.kg

1. Weight of 1m Steel Bar in Kg=d^2/162
2. for Example:- lenth=1m, dia of steel = 20mm    
3.                            20*20/162*1=2.46kg.