Grade 40 vs Grade 60 Rebar — Strength, Uses and How to Tell Them Apart
Updated 4 min readBy OR Steels
Short answer
Grade 60 rebar has a minimum yield strength of 420 MPa (60,000 psi), against 280 MPa (40,000 psi) for Grade 40, so it carries about 50% more stress before yielding. Always buy the grade written on the structural drawings and never substitute without the engineer's approval.
Grade 40 and Grade 60 side by side
| Property | Grade 40 (metric 280) | Grade 60 (metric 420) |
|---|---|---|
| Minimum yield strength | 280 MPa (40,000 psi) | 420 MPa (60,000 psi) |
| Minimum tensile strength | 420 MPa (60,000 psi) | 620 MPa (90,000 psi) |
| Sizes made under ASTM A615 | Smaller sizes only (No. 3–6, about 10–19 mm) | All sizes |
Where each grade is used
- Grade 60 is the usual specification for the main reinforcement of RCC columns, beams, slabs and foundations, because the higher yield strength lets the designer use less steel for the same load.
- Grade 40 is used where the drawings call for it — often lighter structures or secondary bars such as some stirrups and ties.
- Bridges, high-rise and seismic work may call for special requirements (for example low-alloy weldable bars); follow the project specification.
Can you swap one grade for the other?
Not without the structural engineer. Using Grade 40 in place of Grade 60 leaves the member under-reinforced. Using Grade 60 in place of Grade 40 is not automatically safe either: lap lengths, development lengths and bend diameters are calculated from the grade, and a stronger, less ductile bar can change how the member behaves.
How to check the grade you received
- Read the rolled-in markings on the bar: they identify the mill, the bar size and, for Grade 60, the grade.
- Match the heat number on the bundle tag to the mill test certificate.
- Confirm the certificate's yield and tensile values are at or above the minimums in the table above.
Frequently asked questions
Is Grade 60 the same as Grade 420?
Yes. Grade 60 is the inch-pound designation (60,000 psi minimum yield) and Grade 420 is the metric designation (420 MPa) for the same requirement.
Which rebar grade is used for house construction in Pakistan?
Grade 60 is commonly specified for the main bars of RCC houses, but the correct answer is whatever your structural drawings state. If the drawings are unclear, ask the engineer before you order.
Does OR Steels supply both grades?
Yes. OR Steels supplies Grade 60 and Grade 40 TMT rebar, with Grade 75 on request, and every lot comes with its mill test certificate.
