# How to calculate the mass/weight of rebar used in construction site?

How can we calculate the mass or weight of reinforcement bar (rebar) used in construction site. Do anyone know the formula to determine mass of rebar used using its diameter and length? I had once come across such formula while doing my intern in a construction project.

For given diameter of rod of “D” mm and total length of “L” m,

The total mass is given as, **M = (D*D*L)/162**,

where M is mass or weight in kg.

This is the simple formula used in day to day construction practices and record keeping.

For given diameter of rod of “D” mm and total length of “L” m,

The total mass is given as, M=PAI x DxD /4 x 7850

where M is mass or weight in kg.

This is the actual formula used in day to day construction practices and record keeping.

WHAT IS PAI?