Question 1

What is the formula for rebar weight?

Accepted Answer

The simplified formula is Weight (kg/m) = d²/162, where d is the diameter in mm. This is derived from the steel density of 7850 kg/m³ and the circular cross-section area. For D16: 16²/162 = 1.580 kg/m.

Question 2

How much rebar waste should I account for?

Accepted Answer

Typical waste allowances: 3% for simple straight bars, 5% for beams and columns with many bends, and up to 7-10% for complex structures with irregular shapes. Lapping (overlap) adds 40-50 times the bar diameter at each joint.