Canadian rebar is made to CSA G30.18, which sets four common grades: 400R, 500R, 400W and 500W. The number is the minimum yield strength in megapascals, and the letter tells you the type: W bars are weldable and have tighter ductility controls; R bars are "regular". On almost every Canadian building job the bar is 400W, with 500W used where an engineer has designed for it.
The G30.18 grades at a glance
These are the mechanical requirements for the grades in common use, as summarized in the Reinforcing Steel Institute of Canada (RSIC) manual:
| Grade | Minimum yield (MPa) | Maximum yield (MPa) | Minimum tensile (MPa) | Carbon equivalent | Tensile to yield ratio |
|---|---|---|---|---|---|
| 400R | 400 | none | 540 | not limited | at least 1.15 |
| 500R | 500 | none | 675 | not limited | at least 1.15 |
| 400W | 400 | 525 | 540 | 0.55 max | at least 1.15 |
| 500W | 500 | 625 | 625 | 0.55 max | at least 1.15 |
Three things separate the W grades from the R grades:
- A maximum yield strength. A W bar cannot be much stronger than its grade. That sounds odd, but it matters: in an earthquake or overload, engineers want bars to yield in a predictable place and order. A bar that is far stronger than specified can shift where a member fails.
- A carbon equivalent limit of 0.55, which controls the chemistry so the bar can be welded with suitable procedures. Our post on weldable rebar in Canada explains when welding is acceptable.
- Higher elongation and tighter bend tests, so the bar can stretch and bend further before it cracks.
G30.18 has also listed a lower 300R grade in small sizes, but you are unlikely to see it on a building job today.
Ductility: elongation and bend tests
Strength is only half of what a grade tells you. The other half is how far the bar can deform before it breaks. G30.18 checks that with a minimum elongation in a tension test and a bend test around a pin. Values from the RSIC summary for common sizes:
| Bar size | 400R elongation | 400W elongation | 500W elongation | 400R bend pin | 400W bend pin | 500W bend pin |
|---|---|---|---|---|---|---|
| 10M, 15M | 10% | 13% | 12% | 3.5 d | 3 d | 4 d |
| 20M | 10% | 13% | 12% | 5 d | 4 d | 4 d |
| 25M | 9% | 13% | 12% | 5 d | 4 d | 4 d |
| 30M, 35M | 8% | 12% | 10% | 7 d | 6 d | 6 d |
| 45M, 55M | 7% | 12% | 10% | 9 d | 8 d | 8 d |
("d" is the bar diameter.) The W grades stretch further and bend around a tighter pin in testing. That is the reason the standard hook tables allow a smaller finished bend diameter for 400W and 500W bar than for 400R and 500R. For 15M, for example, the RSIC standard hook uses a 90 mm finished bend for W grades and 100 mm for R grades.
Yield strength and capacity by bar size
"15M rebar yield strength" is a common search, but yield strength belongs to the grade, not the size. What changes with size is the force a bar can carry, which is the yield strength times the bar's area:
| Bar | Area | Yield force, 400W (minimum) | Yield force, 500W (minimum) | Tensile force, 400W (minimum) |
|---|---|---|---|---|
| 10M | 100 mm² | 40 kN | 50 kN | 54 kN |
| 15M | 200 mm² | 80 kN | 100 kN | 108 kN |
| 20M | 300 mm² | 120 kN | 150 kN | 162 kN |
| 25M | 500 mm² | 200 kN | 250 kN | 270 kN |
| 30M | 700 mm² | 280 kN | 350 kN | 378 kN |
| 35M | 1,000 mm² | 400 kN | 500 kN | 540 kN |
These are material minimums, not design capacities. In design, CSA A23.3 applies a resistance factor of 0.85 to reinforcement, and it does not allow a specified yield strength above 500 MPa to be used in design calculations.
Searches for "15M rebar shear strength" usually come from people sizing dowels or anchors. A bar's shear resistance in concrete depends on the connection, the concrete and the edge distances, so it is an engineering check, not a number from the grade table.
400W or 500W: when each is used
400W is the default. It is what Part 9 of the Ontario Building Code points to (Grade 400 bar to CSA G30.18 for ICF walls and cold room slabs), what most engineers specify, and what fabricators and suppliers in Ontario carry and bend every day.
500W shows up where higher strength saves steel or relieves congestion: heavily reinforced columns, transfer elements, some precast and civil work. The trade-offs:
- Longer development and lap lengths. A23.3 development length rises in proportion to yield strength, so a 500W bar needs about 25% more than 400W in the same concrete. Our development length guide shows the base numbers.
- Different bend test requirements, as in the table above.
- Crack widths and deflection can govern before strength does, which limits the savings in slabs and beams.
Never swap grades on site. A 500W bar substituted for 400W can have laps that are too short, and a 400W bar in place of 500W is under strength. Grade substitutions go back to the engineer.
How to identify the grade on a bar
G30.18 bars carry rolled-in markings, repeated every 1 to 1.5 m along the bar, in this order: the mill symbol, the bar size, then the grade. Per the identification requirements published by the Ontario concrete industry and RSIC:
- 400 grades: the number 400, or one offset line running through at least five spaces between the ribs.
- 500 grades: the number 500, or two offset lines.
- W grades: the letter W rolled on the bar next to the grade mark.
- R grades: the letter R is not rolled on, so a bar with a 400 mark and no W is 400R.
Bars cut and bent by a fabricator are also tagged by mark, size and grade, and mill test reports trace the bundle back to the heat of steel it came from. If the specification calls for 400W, the mill certificates are how you prove it.
Canadian grades vs US Grade 40, 60 and 80
US rebar follows ASTM standards, with grades named for minimum yield strength in thousands of psi:
| US grade | Standard | Minimum yield | Minimum tensile | Nearest Canadian grade |
|---|---|---|---|---|
| Grade 40 (metric 280) | ASTM A615 | 40,000 psi (about 276 MPa) | 60,000 psi | none in common use |
| Grade 60 (metric 420) | ASTM A615 | 60,000 psi (about 414 MPa) | 90,000 psi | 400R |
| Grade 60 (metric 420) | ASTM A706, low-alloy weldable | 60,000 psi (about 414 MPa) | 80,000 psi | 400W |
| Grade 80 (metric 550) | ASTM A615 | 80,000 psi (about 552 MPa) | 105,000 psi | 500R (closest) |
"Nearest" is approximate: the minimums, maximums and test requirements differ, and US bars are a different set of sizes. Searches like "rebar weight grade 60" are really asking about bar size, because grade does not change weight. A #5 bar is 1.043 lb/ft in every grade. Our Canadian vs US rebar size chart has the full size and weight conversion.
Ordering the right grade
Check the general notes on the structural drawings for the bar grade before ordering. If they say 400W, that is what goes on the bar list and the mill certificates; if certain elements call for 500W, those marks are listed separately so they cannot be mixed up on site.
We supply straight bar in all standard metric sizes from 10M to 55M and fabricate dowels, stirrups, ties and custom shapes to your bar lists. Send us your drawings for a free take-off and quote, or see our rebar products and size chart.
Frequently asked questions
What grade of rebar is used in Canada?
Most Canadian rebar is Grade 400W to CSA G30.18: a 400 MPa minimum yield strength with weldable chemistry and controlled ductility. 500W is used where the design calls for higher strength, and the R grades (400R, 500R) are regular grades without the weldability and ductility controls.
What is the yield strength of 15M rebar?
Yield strength is a property of the grade, not the size. 15M in Grade 400W has a minimum yield strength of 400 MPa and a maximum of 525 MPa. With a 200 mm² area, that means a 15M bar yields at a force of at least 80 kN.
Which rebar is stronger, 400W or 500W?
500W has a higher minimum yield strength (500 MPa vs 400 MPa) and a higher minimum tensile strength (625 MPa vs 540 MPa). Stronger does not mean interchangeable: 500W needs longer development and lap lengths, so only the engineer can substitute one for the other.
Is Canadian 400W the same as US Grade 60?
Close, not identical. US Grade 60 (metric Grade 420) has a minimum yield of 60,000 psi, about 414 MPa. Canadian 400W specifies 400 MPa minimum with a 525 MPa maximum and weldability limits, which makes it closer to ASTM A706 than to plain A615 Grade 60.
Does the rebar grade change its weight?
No. Weight depends only on bar size. A 15M bar weighs 1.570 kg/m in any grade, and a US #5 bar weighs 1.043 lb/ft whether it is Grade 40 or Grade 60.
