Bar bending schedule, without the all-nighter

What is a bar bending schedule (BBS)?

A bar bending schedule is the member-wise list of every reinforcement bar in an RCC structure. For each bar mark it records the diameter, the shape (straight, L, U, crank, stirrup), the cutting length, the number of pieces, and the weight. The bar bender cuts and bends from it, the storekeeper issues steel against it, and the billing engineer measures reinforcement from it — so one wrong line shows up three times. Site teams usually build it in a spreadsheet, member by member, late at night before the steel order goes out. That is the part worth automating; the checking is the part worth keeping human.

Steel weight calculation: the d²/162 rule

Rebar weight per metre is d²/162 kg, where d is the bar diameter in mm. It comes from the density of steel applied to the bar's cross-section, and it is the figure every BBS and every steel challan in India runs on. One worked example: a 16 mm bar weighs 16²/162 = 256/162 ≈ 1.58 kg per metre, so a full 12 m length is about 18.96 kg — call it 19 kg. A bundle of ten such lengths should weigh close to 190 kg on the kanta. The calculator above does exactly this for 6 to 32 mm bars: enter dia, length and count, and read the total in kg — plus bars per tonne, for checking a challan on the kanta.

Cutting length: where bends and hooks go

Weight alone doesn't make a schedule — the cutting length does. A bar that bends is longer along its centre line than its end-to-end dimensions suggest, so the schedule adds hook lengths and subtracts bend allowances before multiplying by d²/162. The commonly used allowances are a deduction of 1d for a 45° bend, 2d for 90° and 3d for 135°, with around 9d–10d added per stirrup hook. Development length and lap length are added on top per the design. These are standard thumb allowances, and the engineer of record reviews and adjusts them against the drawing notes — SiteHisab shows its working for every bar so that review takes minutes, not evenings.

From structural drawings to member-wise BBS

Inside SiteHisab, an AI Drawing Check reads a structural drawing sheet — beam schedules, slab details, footing layouts — and turns it into member-wise quantities and a bar bending schedule: marks, diameters, shapes, cutting lengths, counts and weights, organised floor by floor through the per-floor quantity wizard. Nothing goes into your registers on trust: every extracted member lands as an editable line for you to check against the drawing and correct where the sheet is ambiguous. Yearly and one-time plans include 50 Drawing Checks and monthly includes 5 a month; importing a BOQ you already have from a spreadsheet or CSV is free and uses no checks. The reviewed quantities flow straight into your BOQ register, built from thousands of published government Schedule-of-Rates items or your own uploaded BOQ.

Reconcile BBS steel against challans

The schedule tells you what the structure needs; the daily site hisab tells you what actually arrived. SiteHisab records material receipts — including steel challans — alongside labour attendance and progress, so you can put the BBS demand for a floor next to the tonnage received and issued. If 4.2 t of 16 mm came in against a schedule that needs 3.8 t, you ask the question the same week, not at project close. The same records feed RA bills received and checked, with GST and TDS worked out to the net payable.

A free steel calculator — and a BBS app when you need more

The steel weight calculator on this page is free, needs no login, and lives with the rest of the free construction calculators. The full bar bending schedule app — drawings to member-wise BBS, per-floor quantities, BOQ, daily hisab, bills and money — is one plan: ₹99/month, ₹999/year, or ₹4,999 one-time to own it forever, with a 14-day free trial (the trial includes 15 AI Drawing Checks); the first real charge comes only after the trial, and you can cancel anytime. It runs in the browser on your phone or laptop, installs to the home screen, and keeps your data in your own account. More on how we work is on the about page.