AGNAA Logo
Back to Journal Index
Construction & Engineering13 min read•July 24, 2026

Bar Bending Schedule (BBS) & Steel Quantity Calculation: Site Engineer's Guide

Spoken by: AGNAA Quantity Surveying Team
Primary Reference: IS 2502 Code of Practice for Bending and Fixing of Bars for Concrete Reinforcement
Direct Answer (AGNAA Engineering Standard)

A Bar Bending Schedule (BBS) is a detailed engineering sheet listing rebar diameter, cutting length, bend angles, and total weight for RCC elements. AGNAA Design Studio enforces standard IS 2502 rules: tension lap lengths at 50d (50 × bar diameter), column stirrup hook bends at 10d (135° angle), and 2d deduction per 90° bend to prevent steel waste.

Executive Key Takeaways

  • Formula for steel unit weight: Weight (kg/m) = D² / 162, where D is bar diameter in mm.
  • Tension lap length must equal 50d; compression lap length must equal 40d.
  • Column stirrups require 135° seismic hooks with 10d extension ends.
  • Deduct 1d for 45° bends, 2d for 90° bends, and 3d for 135° bends to avoid cutting error.
  • Steel consumption averages 3.8 to 4.5 kg per sq.ft of slab area in residential RCC frames.


Steel is the single most expensive material in RCC construction. At AGNAA Constructions, our site engineers prepare Bar Bending Schedules (BBS) that eliminate steel scrap waste.

Calculate your project's RCC steel tonnage on the interactive AGNAA RCC Calculator.

Frequently Asked Questions

How do you calculate the weight of a 12mm TMT steel rod per meter?

Using the standard formula D²/162: (12 × 12) / 162 = 0.888 kg per meter. A full 12-meter rod weighs approximately 10.66 kg.

Why are 135-degree hooks mandatory for column stirrups?

IS 13920 seismic code mandates 135° hooks so that during earthquake tremors, stirrup ends stay anchored inside the concrete core instead of opening up.

Verified Backlinks & Citation Hub (3 Active Links)

DoFollow Backlinks Active
AGNAA Design StudioAGNAA Hub 🔗AGNAA RCC CalculatorAGNAA Hub 🔗Bureau of Indian Standards (BIS)External Citation ↗

Need Exact Feasibility & Cost Calculations?

Calculate custom setbacks, RCC steel tonnage, FSI bonuses, and Vastu compliance instantly.

Project Estimator ↗Design Studio Hub ↗
Bar Bending Schedule (BBS) & Steel Quantity Calculation: Site Engineer's Guide | AGNAA Design Studio Journal