Rebar Shape Codes Explained

Every piece of steel reinforcement used on site follows a defined system. Behind each bent bar is a set of standards, dimensions and shape codes designed to make reinforced concrete safer, more efficient and easier to build.

Rebar shape codes provide a shared reference for engineers, fabricators and contractors. From simple straight bars to complex links and cranked reinforcement, these codes ensure reinforcement is cut, bent and supplied exactly as specified.

This guide explains what rebar shape codes are, why they matter, and how they’re used in UK construction.

What are rebar shape codes?

Rebar shape codes are standardised references used to describe how a steel reinforcement bar is bent. Instead of relying on written descriptions or drawings alone, each rebar shape is assigned a numerical code that defines its geometry, bend angles and dimensions.

These shape codes are used across:

• Reinforcement bar schedules
• Fabrication drawings
• Cut-and-bent rebar production
• On-site fixing and inspection

For anyone working with reinforcing bars for concrete, shape codes remove ambiguity and help ensure the steel delivered matches the engineer’s intent.

Each shape code represents a specific configuration of bends and straight lengths. Dimensions are referenced using letters such as A, B and C, and the total bar length is calculated using standard equations that account for bend radii and bar diameter.

Which standards govern rebar shape codes in the UK?

In the UK, rebar shape codes are defined by BS 8666, with the current standard being BS 8666:2020.

This standard sets out the rules for:

• Scheduling reinforcement bars
• Dimensioning and tolerances
• Cutting and bending reinforcing steel
• Shape codes for standard rebar shapes

BS 8666 works alongside product standards such as BS 4449 (rebar), BS 4483 (reinforcing fabric) and BS 6744 (stainless reinforcement). Together, these standards ensure that steel reinforcement used in concrete construction meets consistent quality, safety and performance requirements.

Common rebar shapes and where they’re used

When people talk about rebar shape codes, they’re really talking about a shared visual language. Rather than lengthy descriptions, each reinforcing bar shape is given a number that tells us exactly how it should be bent, cut and supplied.

Below are some of the most commonly requested rebar shapes we bend and supply at 7 Steel Service.

Straight bars - Shape Codes 00 & 01

The simplest form of steel reinforcement bar.

Used for stock lengths, laps, ties and general bar reinforcement where no bends are required.

L-shaped bars - Shape Codes 11 & 12

A single 90° bend, with or without a radius.

Commonly used as starter bars, edge reinforcement and for tying slabs into walls or upstands.

U-bars - Shape Code 13

A continuous 180° bend forming a U shape.

Often used in concrete reinforcement bars for pile caps, ground beams and slab edges.

Cranked bars - Shape Code 26

Angled bends that step the bar up or down between levels.

Typically used in suspended slabs, beams and areas where load transfer changes elevation.

Links and ties - Shape Codes 33, 41 and similar

Closed or semi-closed shapes used to restrain main reinforcement bars.

Essential for columns, beams and cages where confinement and stability are critical.

Circular and spiral bars - Shape Codes 75 & 77

Used in piling cages, curved concrete elements and circular columns.

These shapes are precision-bent off-site to reduce waste and speed up installation.

Non-standard bends - Shape Code 99

Any reinforcing steel bar that doesn’t fit a standard profile.

At 7 Steel Service, these are produced directly from drawings, with close attention to tolerances and buildability.

While the shapes themselves may look straightforward, every rebar shape code is governed by specific rules around dimensions, bend radii and tolerances, all of which ensure reinforcement arrives on site ready to fix.

Why rebar shape codes are essential

From a practical perspective, rebar shape codes exist to make construction simpler, safer and more predictable.

Using standard shape codes helps to:

• Reduce on-site cutting and bending
• Minimise steel waste
• Improve accuracy during installation
• Lower health and safety risks
• Speed up reinforcement installation

When reinforcement bars are cut and bent off-site to the correct shape, they arrive ready to place, reducing the need for rebar cutters, shears or bending equipment on site.

For larger projects, shape-coded rebar also improves cost certainty, as material quantities and bending requirements are clearly defined upfront.

Standard vs non-standard rebar shapes

Most reinforcement requirements can be met using standard rebar shape codes, which is always the preferred approach.

Standard shapes are:

• Faster to produce
• Easier to schedule
• More predictable in cost
• Fully compliant with British Standards

However, some projects require non-standard or bespoke bends. These are usually assigned Shape Code 99 and supported by drawings or sketches to show how the bar should be formed.

At 7 Steel Service, we regularly work with both standard and bespoke reinforcement bars, helping clients find practical solutions that still meet design intent and site constraints.

How bar bending schedules use shape codes

A bar bending schedule brings everything together. It sets out:

• Bar diameter (e.g. 10mm, 12mm, 16mm rebar)
• Bar length and quantity
• Shape code
• Steel grade
• Location within the structure

For reinforcement bar suppliers and fabricators, the shape code is the key reference that dictates how the rebar is cut and bent. For steel fixers, it provides clarity on how each bar should be placed within the concrete.

Clear schedules lead to smoother production, fewer queries and less rework on site.

Technical support for reinforcement detailing and fabrication

Rebar shape codes are more than just numbers on a schedule. They’re a practical tool that helps ensure steel reinforcement arrives on site ready to install, compliant with UK standards and suited to the demands of the structure.

At 7 Steel Service, our focus is on getting reinforcement bars cut and bent accurately, consistently and on time. Whether that’s standard rebar shapes or more complex reinforcement requirements.

Our reinforcement is produced from UK-sourced recycled steel and cut and bent with precision to meet project specifications.

If you’re working with bar bending schedules, shape codes or reinforcement detailing and want support from a team that deals with this every day, getting the fundamentals right makes all the difference.

Contact us