Here’s how to build one correctly, the formula behind it, and a faster way to get it done.
What Is a Bar Bending Schedule?
A Bar Bending Schedule is a table listing every reinforcement bar in a structural element — its diameter, shape, cutting length, number of bars, and total weight — used to order the exact quantity of steel needed and to guide site-level bar bending and placement. It’s a mandatory part of any detailed RCC estimate and a standard requirement in CPWD/tender documentation.
A complete BBS entry includes:
- Bar mark / member — which structural element (footing, column, beam, slab) the bar belongs to
- Diameter — 8mm, 10mm, 12mm, 16mm, 20mm, 25mm etc.
- Shape code & bend details — straight, L-bend, U-bend, stirrup, as per standard bend codes
- Cutting length — actual length of bar including bends and hooks, minus deductions
- Number of bars
- Unit weight and total weight
The Steel Weight Formula (The Part Everyone Has to Memorize)
Every BBS calculation comes down to one formula:
Unit Weight (kg/m) = d² ÷ 162
where d is the bar diameter in millimetres. Multiply unit weight by the cutting length (in metres) and the number of bars to get total weight for that item.
Quick Reference: Standard Bar Weights per Metre
| Diameter | Weight (kg/m) |
|---|---|
| 8 mm | 0.395 |
| 10 mm | 0.617 |
| 12 mm | 0.888 |
| 16 mm | 1.580 |
| 20 mm | 2.470 |
| 25 mm | 3.850 |
| 32 mm | 6.310 |
How to Prepare a BBS, Step by Step
- Identify each structural member from the drawing — footings, columns, beams, slabs — and list them separately.
- Note bar diameter and spacing from the reinforcement drawing for each member.
- Calculate cutting length for each bar shape — this includes the clear span/height plus development length and hook allowances, minus concrete cover deductions at bends.
- Count number of bars per member based on spacing (e.g., stirrup spacing of 150mm over a 3m column height).
- Apply the weight formula (d² ÷ 162 × length × count) to get total weight per item.
- Sum by diameter to get total steel tonnage — this is the number that goes into your BOQ and your steel order.
💡 Why manual BBS calculation is risky
A single missed deduction or wrong bend allowance across 100+ bar entries can throw your steel quantity off by tons — either you over-order (wasted budget) or under-order (site delay mid-pour). Our Civil Work Estimate & BOQ Template includes an automatic Bar Bending Schedule sheet — enter member dimensions and bar spacing, and it calculates cutting length, weight, and total tonnage for you, feeding straight into your BOQ’s steel line item.
Build It in Excel, or Skip Straight to a Working Template
A BBS sheet in Excel is very buildable — the formula itself is simple — but a robust one needs correct deduction logic for every bend type (L-bend, U-bend, stirrup hooks) and clean linking to your quantity takeoff and BOQ, which is where most manually-built sheets get shaky.
Our Professional Civil Work Estimate & BOQ Template ships with the BBS sheet pre-built and connected to the rest of the estimate — steel quantities flow straight into your rate analysis and abstract of cost, with no separate reconciliation needed.
Special Launch Offer
Get Auto BBS + Full BOQ Template for ₹249 ₹999
Automatic Bar Bending Schedule, Rate Analysis, BOQ & Dashboard in one Excel file
Frequently Asked Questions
What is the formula for steel weight in BBS?
Unit weight (kg/m) = d² ÷ 162, where d is the bar diameter in mm. Multiply by cutting length and number of bars for total weight.
Why is Bar Bending Schedule important?
It gives an exact, verified steel quantity for ordering and site cutting/bending, avoiding both material wastage and site-level shortages, and is required for CPWD/tender documentation.
What is included in a BBS sheet?
Bar mark, diameter, shape/bend code, cutting length, number of bars, unit weight, and total weight — grouped by structural member and summarized by diameter.
Can Excel calculate Bar Bending Schedule automatically?
Yes — with the right formulas linking member dimensions, bend deductions, and the weight formula, Excel can auto-calculate a full BBS, which is exactly how the BBS sheet in our BOQ template works.
Related: RCC Cost per Sq Ft with Material · Cement Calculator for Slab · RCC Construction Cost per Sq Ft