Bar Marks & the Bar Bending Schedule
Bar marks and the Bar Bending Schedule (BBS) are the backbone of every reinforced concrete project — translating the structural engineer’s design intent into precise fabrication and delivery instructions. This guide explains what bar marks are, how a BBS is structured, and how to use it to order German-standard B500B reinforcement efficiently.
What Is a Bar Mark?
A bar mark is a unique alphanumeric identifier assigned to every distinct reinforcing bar type in a reinforced concrete element. It appears on the structural drawing as a tag alongside the bar symbol, and on the Bar Bending Schedule as the key that links the drawing to the fabrication instructions.
Two bars share the same bar mark only if they are identical in every respect: the same grade (e.g., B500B), diameter (e.g., 16 mm), shape code (e.g., BS 8666 shape code 25), and all bending dimensions. If even one dimension differs, they receive different bar marks — because the fabricator must produce each mark as a separate programmed cut.
Bar marks are typically assigned sequentially per structural element (e.g., B1 through B24 for a single beam, C1–C12 for a column), or globally across a drawing package. The important thing is consistency: the same bar mark must appear on the drawing, the BBS, the delivery note, and the bundle tag on site.
The Bar Bending Schedule: Structure and Columns
A Bar Bending Schedule is a tabulated document — typically an A3 or A4 spreadsheet — that lists every bar mark required for a structure or pour. The standard column layout under BS 8666 is:
| Column | Content | Notes |
|---|---|---|
| Member | Structural element (e.g., “Beam B3”) | Groups bars by location |
| Bar Mark | Unique identifier (e.g., “01”, “B3-T1”) | Must match drawing |
| Type/Grade | B500B, B500C, etc. | DIN 488 / EN 10080 grade |
| Size (dia, mm) | 8, 10, 12, 16, 20, 25, 32… | Nominal diameter |
| No. of Members | How many identical structural elements | Multiplier for quantity |
| No. of Bars in Each | Bars per element per mark | e.g., 4 top bars per beam |
| Total No. | No. of Members × No. of Bars in Each | Total quantity to fabricate |
| Shape Code | BS 8666 two-digit code | e.g., 00, 25, 11 |
| A, B, C, D, E (mm) | Leg dimensions to centreline | Only those applicable to shape |
| Total Length (mm) | Cutting length per bar | Calculated from legs + deductions |
| Weight (kg) | Total No. × cut length × kg/m | kg/m = d²(mm) × 0.00617 |
The weight column is the most important for procurement. It drives the mill order quantity, the shipping weight for freight calculation, and the invoice. Errors in weight calculations — typically from forgetting bend deductions or using wrong kg/m factors — are one of the most common sources of rebar shortfall on site.
Calculating Weight from the BBS: The Formula
The unit weight of a reinforcing bar is derived from the steel density (7,850 kg/m³) and the circular cross-section formula:
kg/m = d²(mm) × 0.00617
where d is the nominal diameter in millimetres. For common B500B diameters:
| Dia (mm) | kg/m | Cross-section (mm²) |
|---|---|---|
| 8 | 0.395 | 50.3 |
| 10 | 0.617 | 78.5 |
| 12 | 0.888 | 113 |
| 16 | 1.58 | 201 |
| 20 | 2.47 | 314 |
| 25 | 3.85 | 491 |
| 32 | 6.31 | 804 |
| 40 | 9.86 | 1,257 |
Example: 120 bars of 16 mm diameter at a cut length of 3,850 mm each:
Weight = 120 × 3.850 m × 1.58 kg/m = 730 kg (approximately 0.73 t).
Common BBS Errors and How to Avoid Them
The most frequent mistakes on Bar Bending Schedules that result in material shortfall or excess waste:
- Omitting bend deductions. Dimension A on a bent bar is the leg length to centreline, not the cut length. Each 90° bend shortens the cut length by approximately 2r + d. Forgetting deductions leads to bars that are cut too long and waste material, or too short if the schedule is later corrected under-compensated.
- Wrong shape code for the geometry. Using shape code 00 (straight) for a bar that is actually bent causes the fabricator to supply an unworkable bar. Always confirm shape code against the structural drawing geometry before issuing the BBS.
- Duplicate bar marks. Two different geometries assigned the same bar mark cause confusion at the cutting machine and potentially the wrong bar placed in the wrong location.
- Mixing grade designations. Specifying B500B in some rows and an unlabelled “high-yield” in others — ensure every row carries a clear grade reference, especially for export projects crossing multiple national code jurisdictions.
- Rounding errors in quantity calculations. Rounding down on total number of bars and cutting lengths compounds across hundreds of bar marks. Round up quantities; it is always cheaper to have a small surplus than to reorder an emergency shipment.
Using the BBS to Order from Steel Rebar Germany
When you submit a quote request to Steel Rebar Germany, attaching your completed BBS dramatically accelerates the quotation process. From the BBS we can extract:
- Total tonnage per diameter and grade — the basis for mill pricing
- Whether straight bar or cut-and-bent supply is required
- Packing requirements — seaworthy bundles (~2 t each), container or break-bulk, bundle tagging by bar mark
- Documentation package — EN 10204 3.1 Mill Test Certificates referenced to each heat/bundle
For export projects, we include Certificate of Origin and CE/DoP documentation alongside the MTC. All documentation is in English as standard. Submit your BBS via our quote request form and reference our products page for available diameters and grades.
See also: Rebar Shape Codes (BS 8666) Explained — the companion guide to this article.
Frequently Asked Questions: Bar Marks & BBS
Can two bars in the same structure share the same bar mark?
What happens if I submit a BBS with errors to the fabricator?
Is there a standard software for producing a BBS?
How do I account for wastage when ordering from the BBS weight total?
Does Steel Rebar Germany supply bundles tagged by bar mark?
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