30 9 月, 2026
Deformed Bar vs Round Bar: Which Should You Use for Reinforcement?
For structural reinforcement you need a deformed (ribbed) bar, because the ribs grip the concrete and transfer load. A plain round bar is smooth and has far less bond, so it is not used as main reinforcement; it is used for ties, dowels, pins and general machining stock. The two are the same steel, formed differently.
Why the ribs matter
Concrete and steel work together only if the steel cannot slip. The ribs on a deformed bar provide mechanical interlock with the concrete, which is what allows the bar to develop its design stress. A plain round bar relies on adhesion alone, so codes restrict it to secondary or non-structural duties.
Weight reference for both products
| Nominal diameter (mm) | Deformed bar weight (kg/m) | Round bar weight (kg/m) |
|---|---|---|
| 6 | 0.222 | 0.222 |
| 8 | 0.395 | 0.395 |
| 10 | 0.617 | 0.617 |
| 12 | 0.888 | 0.888 |
| 14 | 1.21 | 1.21 |
| 16 | 1.58 | 1.58 |
| 18 | 2 | 2 |
| 20 | 2.47 | 2.47 |
| 22 | 2.98 | 2.98 |
| 25 | 3.85 | 3.85 |
| 28 | 4.83 | 4.83 |
| 32 | 6.31 | 6.31 |
| 36 | 7.99 | 7.99 |
| 40 | 9.87 | 9.86 |
Theoretical masses. Deformed bar values follow GB 1499.2-2024 nominal diameters; round bar values follow GB/T 702-2017. Confirm the size and grade in your enquiry.
How to specify
- State the product — deformed bar or plain round bar — and the standard
- State the grade, for example HRB400E for reinforcement
- State the nominal diameter, the length and the delivery form
- For reinforcement, ask for the mill test certificate with the mechanical results
Related reading
Frequently asked questions
Can round bar be used instead of deformed bar for reinforcement?
Only where the design and the code allow it, typically for secondary items such as ties and dowels. Main reinforcement relies on the ribs of a deformed bar to develop bond with the concrete.
Do deformed bar and round bar of the same diameter weigh the same?
Closely. Theoretical mass depends on the nominal diameter, so a deformed bar and a round bar of the same nominal diameter have almost the same mass per metre. See the table above.
What grade are deformed bars?
Common reinforcement grades include HRB400E and HRB500E, which denote the nominal yield strength and the seismic (E) requirement. The grade must be stated in the order.
Tell us the standard, grade, form and size you need and we will quote against it. See our steel product catalogue, how we inspect and certify each order, or request a quotation.