Steel Calculators

The standard formula is W = d² / 162.2, where d is the bar diameter in millimeters and W is the weight in kg per meter. For example, a 12 mm bar weighs 12² / 162.2 ≈ 0.888 kg/m. This formula assumes a steel density of 7850 kg/m³ and works for all plain round and deformed bars conforming to standard specifications.

Fe500 or Fe500D TMT bars are the most common choice for residential buildings. Fe500 has a yield strength of 500 MPa, which allows engineers to use slightly less steel compared to the older Fe415 grade while maintaining the same structural capacity. Fe500D adds better ductility (the 'D' stands for ductile), making it preferable in seismic zones. Always follow the grade specified on your structural drawings.

Measure the window opening width and height, decide on the bar spacing (typically 100–150 mm center-to-center for vertical bars), and choose the section — usually 12 mm square bar or 16 × 3 mm flat bar for residential grills. Count the number of horizontal and vertical members, multiply each by its cut length plus 50–75 mm extra per end for welding or embedding into the frame, then convert total length to weight using the section's kg/m value.

A standard allowance is 3–5 % of the total calculated weight for straight bars and 5–8 % when there are many bent shapes (stirrups, cranked bars, hooks). Waste comes from standard mill lengths (usually 12 m) not dividing evenly into your cut lengths, plus offcuts from bending. Ordering a mix of 9 m and 12 m lengths, where available, can reduce waste significantly on jobs with varied cut sizes.