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Steel Rebar Grades, Sizes and Standards Explained

A Practical Guide for Steel Procurement and Construction Professionals

The quality of steel rebar has a significant impact on reinforced concrete structures, including structural safety, construction feasibility, and material costs.

For steel purchasers, contractors, and engineers, understanding carbon steel rebar grades, size standards, and packaging methods under different market and international procurement and project execution standards is crucial.

This document aims to provide a concise and professional overview of global rebar standards, primarily covering Chinese (GB), European (EN), and American (ASTM) standards.

Rebar Grades Affecting Yield Strength and Standard

There are differences in grade for reinforcing steel depending on the minimum yield strength and the grade name will depend on the applicable standards and it differences from one region to another.

China Standard –GB 50010 /GB1499.2
The generally adopted hot-rolled ribbed rebar grades in China are as follows:
HRB335 Steel Rebar
Minimum yield strength: 335 MPa
For ordinary reinforced concrete work.
HRB400 Steel Rebar
Minimum yield strength: 400 MPa
Residential, Commercial and Infrastructure applications The most common.
HRB500 Steel Rebar
Minimum yield strength: 500 MPa
Suitable for high load, massive and high-rise buildings
Definition of Grade:
HRB = Hot Rolled Ribbed Bar
The number denotes the minimum yield strength (MPa).

European Standard – EN 10080(B500 Series)
European rebar standards focus heavily on ductility which is important for seismic performance.
B500A – 500 MPa, low ductility
B500B – 500 MPa, medium ductility
B500C – 500 MPa, ductility (used in seismic constructions)
Of those the B500C is the most common.

USA Standard – ASTM A615 / ASTM A706
Rebar strengths are defined differently in the US market (where ksi is used instead of MPa):
Grade 40 – 40 ksi ≈ 275 MPa
Grade 60 – 60 ksi ≈ 420 MPa (most widely used)
Grade 75 – 75 ksi ≈ 520 MPa
Note:
ASTM A615: carbon steel reinforcement standard
ASTM A706: enhanced weldability and ductility and is commonly used for seismic applications

Standard Rebar Sizes and Diameters

Rebar size standards differ across regions and should be carefully matched during procurement.

Common Rebar Diameters in China (mm)
6, 8, 10, 12, 14, 16, 18, 20, 22, 25, 28, 32, 36, 40
Small diameters (≤12 mm): slabs, stirrups, light structures
Large diameters (≥16 mm): beams, columns, foundations, bridges
Common Rebar Diameters in Europe (mm)
6, 8, 10, 12, 16, 20, 25, 32, 40

European projects typically use a more standardized diameter range, improving construction efficiency.

U.S. Rebar Size Chart (# Bar System)
U.S. rebar is identified by bar numbers, not direct metric diameters:
#3 → 9.5 mm
#4 → 12.7 mm
#5 → 15.9 mm
#6 → 19.1 mm
#7 → 22.2 mm
#8 → 25.4 mm
#9 → 28.7 mm
#10 → 32.3 mm

Procurement tip:
Always convert # bar sizes to metric diameters when sourcing rebar internationally to avoid weight and tolerance discrepancies.

Length, Packaging, and Delivery of Rebar

Standard Lengths
9 m
12 m
Custom cut-to-length is available on request.

Type of Packaging
Loose bundles – for large diameter bars
Tied rebar – the most popular way for container and bulk shipments
Coiled rebar (small diameters – 6-10 mm or similar, suitable for automated processing)

Tips to Select the Best Rebar for Your Project

From a procurement and engineering outlook:

Check design codes and local compliance requirements before choosing grades.
For seismic or high-safety buildings only consider ductility and not yield strength.
Check for compatibility with standards/bar size system/length tolerances for your export project.

Proper length and packaging can also prevent waste and reduce handling fees.

Although steel rebar is a standardized building material, varying grades, size systems, and regional standards can significantly affect project cost, compliance, and structural performance.
For steel purchasers and construction professionals, understanding these differences means safer designs, easier procurement, and better value sourcing.

ROYAL GROUP

Address

Kangsheng development industry zone,
Wuqing district, Tianjin city, China.

E-mail

sales01@royalsteelgroup.com

Phone

Sales Manager: +8613652091506

Hours

Monday-Sunday: 24-hour Service

Post time: Feb-03-2026