Bar Bending Schedule Calculator – BBS, Cutting Length & Weight
Build a Bar Bending Schedule You Can Read and Check
Create bar marks one by one, see a shape preview and the formula being used, calculate cutting length and nominal weight, group totals by diameter, estimate material cost, and pass the finished schedule to the Rebar Cutting Optimizer.
Project & pricing settings
Create one bar mark
All dimensions below are in millimetres. For geometry modes, A/B/C are treated as centreline dimensions. The net adjustment can be positive (extra hook/extension) or negative (deduction) and must come from your project detailing method.
Bar bending schedule
Every row shows the actual method used to obtain its cutting length. Use the schedule as a planning/estimating aid and compare it with the issued BBS before fabrication.
| Mark | Member | Shape / method | Preview | Ø mm | Grade | Qty | Cut length | kg/m | Each kg | Total kg | Cost |
|---|
Weight by diameter & grade
| Group | Pieces | Total length | Weight | Cost |
|---|
Steel weight chart
Table of contents
What the BBS results mean
A bar bending schedule identifies each reinforcement type with a bar mark, member/location, nominal diameter, grade, quantity and cutting length. This calculator also adds nominal mass per metre, weight per bar, total weight and a diameter/grade summary for estimating and procurement.
The cutting length is the straight material length required before bending. For fabrication, the approved project BBS or governing shape-code rules must take precedence.
How to use this BBS calculator
- Enter project reference and steel price if you want a cost summary.
- Create a bar mark and select its diameter, grade and quantity.
- If an approved cutting length already exists, select Approved cutting length and enter it in A. This is the recommended mode.
- For preliminary geometry only, select a simple shape and enter centreline dimensions. Review the displayed formula.
- Enter an explicit net adjustment only when you know the project/detailing deduction or hook extension.
- Add the bar mark and repeat for the full schedule.
- Review the diameter chart and totals, export CSV/PDF, or send the approved lengths to the Rebar Cutting Optimizer.
Worked example
Suppose bar mark B1 is a 16 mm beam bar with an approved cutting length of 4,250 mm and quantity 12. The calculator uses 4.25 m per bar. With a nominal 16 mm unit mass of about 1.58 kg/m, one bar weighs about 6.71 kg and 12 bars weigh about 80.5 kg. If the entered steel price is $1.10/kg, the estimated material value for that bar mark is about $88.6.
Nominal unit mass = (π/4 × d²) × 7,850 / 1,000,000 kg/m
Common BBS mistakes
- Using external leg dimensions where a project shape code expects centreline or other defined dimensions.
- Applying generic bend deductions or hook allowances without checking the governing standard/project detail.
- Confusing total bar length with cutting length per bar.
- Mixing grades or diameters under the same bar mark.
- Sending preliminary estimated geometry to fabrication as though it were an approved BBS.
- Ignoring revisions to drawing/BBS references.
Assumptions & limitations
- The default Approved cutting length mode performs no bend deduction; it trusts the length you enter.
- Simple shape modes are transparent centreline geometry only: straight A, L = A+B, U = A+2B, rectangular link = 2A+2B, ring = πD and custom = A+B+C, followed by your explicit net adjustment.
- The calculator does not automatically claim compliance with BS 8666, ACI SP-66, AS 3600 or any other detailing standard.
- Actual bar mass may vary slightly due to manufacturer tolerances; nominal weight assumes 7,850 kg/m³.
- Fabrication bend radii, anchorage, hooks, couplers, lap splices and shape-code-specific deductions must come from the applicable project standard.
Questions about bar bending schedules & cutting length
What is a bar bending schedule?
A BBS is a structured list of reinforcement bar marks, sizes, shapes, quantities and cutting/bending information used for detailing, procurement and fabrication control.
What is the safest input for this calculator?
The approved cutting length from the issued BBS. Choose “Approved cutting length” and enter that value directly.
Why does the calculator ask for a net adjustment?
Simple geometry alone does not capture all code/project bend deductions and hook extensions. The adjustment field makes any addition or deduction explicit instead of hiding an assumption.
How is bar weight calculated?
Nominal kg/m is calculated from the selected diameter and steel density. Row weight = kg/m × cutting length × quantity.
Can I send the schedule to the cutting optimizer?
Yes. The “Send schedule to Rebar Optimizer” button stores the bar marks, diameters, grades, quantities and cutting lengths in the browser so the optimizer can load them on the same site/browser.
Sources & further reading
- Reuven Engineering Tools — Rebar Scheduling & Detailing — example of shape-code scheduling, cutting lengths and weight summaries.
- Cutting Length Calculator — Cut & Bend — examples of bent-up bars and shape-driven cutting-length workflow.
- Reuven Engineering Tools — Rebar Weight — nominal bar mass formula using 7,850 kg/m³.
- BS 8666:2020 — Scheduling, dimensioning, bending and cutting of steel reinforcement for concrete.
- ACI SP-66 — Detailing Manual (reinforcement detailing reference).
Methodology — how this calculator works
- Read the bar mark, member, diameter, grade, quantity and selected calculation mode.
- Determine cutting length from either the approved length or the displayed simple centreline formula.
- Add the user-entered net adjustment. Negative values deduct length; positive values add length.
- Calculate nominal mass per metre from the nominal diameter and 7,850 kg/m³.
- Calculate each-bar weight and multiply by quantity.
- Group total pieces, lengths, weights and costs by diameter + grade.
- Export the schedule or pass the resulting approved lengths to the stock-bar optimizer.
Row weight = nominal kg/m × cutting length (m) × quantity