The number after the word grade is a minimum yield strength in ksi. What ASTM A615 asks for in yield, in tensile and in elongation, by grade and by bar size, in both editions of the table.
← Back to the calculatorRead each row as yield first, tensile second. Grade 60 is 60 000 psi yield against 80 000 psi tensile in the 2020 edition — the grade name is the first number, not the second. Where the two editions disagree, section 01 unpacks it and section 02 prints both tables in full.
The two editions do not print the same tensile floors. Grade 60 is 90 000 psi [620] in ASTM A615/A615M-12 and 80 000 psi [550] in A615/A615M-20; Grade 80 went from 105 000 [725] to 100 000 [690]; Grade 75 [520] is in the 2012 edition and not in the 2020 one; Grade 100 [690] was added to the specification in 2015 and appears only in the 2020 one. The yield floors did not move at all. So the edition is part of the number, not a footnote to it.
Which edition applies is a contract question. Ordering and acceptance follow the edition named on the drawings or in the contract: a bar bought against A615/A615M-12 is accepted against the 2012 table, and the 2020 table is not the basis for accepting or rejecting it. That is why the columns below are printed as two columns instead of one “current” answer — this difference surfaces when a delivery is argued over, not when it is designed.
The number after the word grade is a minimum yield strength in ksi. Grade 60 is 60 000 psi; Grade 40 is 40 000 psi; Grade 100 is 100 000 psi. §1.2 says exactly that: bars are of four minimum yield strength levels, designated Grade 40 [280], Grade 60 [420], Grade 80 [550] and Grade 100 [690] in the 2020 edition.
Minimum is the operative word. A heat can test at 67 ksi yield and still ship as Grade 60 — the grade is a floor, not a measured value, and the actual number is on the mill certificate. What the grade buys you is a promise about the lowest bar in the lot, which is the one a design has to survive.
The tensile floor is a second, separate promise, and it is the one that gets misquoted. It is not the yield rounded up, and the same figure turns up in two rows with two meanings: 60 000 psi is a Grade 40 tensile and also a Grade 60 yield, while 40 000 psi is a Grade 40 yield and not its tensile — the tensile beside it is 60 000. That is where most of the confusion in this topic starts.
Two printings of the same table, printed as two columns: the third is Table 2 of ASTM A615/A615M-12, the fourth is Table 2 of ASTM A615/A615M-20. Yield and tensile sit next to each other so they are read together; every figure is psi with the metric value in brackets, and the ratio in the last column is arithmetic on the two to its left.
| Grade | Min yield psi [MPa] | Min tensile, A615/A615M-12 | Min tensile, A615/A615M-20 | Tensile ÷ yield |
|---|---|---|---|---|
| Grade 40 [280] | 40 000 [280] | 60 000 [420] | 60 000 [420] | 1.50 |
| Grade 60 [420] | 60 000 [420] | 90 000 [620] | 80 000 [550] | 1.50 / 1.33 |
| Grade 75 [520] | 75 000 [520] | 100 000 [690] | — | 1.33 |
| Grade 80 [550] | 80 000 [550] | 105 000 [725] | 100 000 [690] | 1.31 / 1.25 |
| Grade 100 [690] | 100 000 [690] | — | 115 000 [790] | 1.15 |
Swipe the table sideways on a phone.
Ordering and acceptance follow the edition named on the drawings or in the contract. The two tensile columns are not interchangeable at settlement: a bar bought against A615/A615M-12 is checked against the 2012 column, whichever column happens to be on the screen.
Read the dashes before the numbers. Grade 75 [520] is in the 2012 edition and not in the 2020 edition; Grade 100 [690] was introduced in the specification in 2015, which the 2020 edition states in NOTE 1 to §1.2, so it is absent from the 2012 printing. A Grade 75 bar in the yard is not counterfeit — it is a bar made to the older edition, and drawings written before the change still call for it.
Where the editions differ, the difference is always in the tensile floor, never the yield: Grade 60 went from 90,000 to 80,000 psi and Grade 80 from 105,000 to 100,000. So a table quoting 90 ksi for Grade 60 is not wrong, it is quoting the older printing. A table quoting 40,000 psi as the tensile of Grade 40 is a different kind of mistake: 40,000 is the yield in that same row, and the tensile beside it is 60,000.
The ratio column is arithmetic on the two columns to its left — 60 000 ÷ 40 000 = 1.50, 115 000 ÷ 100 000 = 1.15 — and the standard prints its own version of it. NOTE 1 to §1.2 of the 2020 edition says the lower grades have specified tensile-to-yield ratios of 1.25 to 1.50, and Grade 100 has 1.15, with a lower margin of safety and less warning before failure as a consequence. That is why Grade 100 is not a free upgrade on a drawing that was detailed for Grade 60.
The third requirement in Table 2 is elongation in 8 in [200 mm], and unlike yield and tensile it is not one number per grade — it is one number per grade per bar size. The gauge length does not change with the bar, so the percentage is comparable between grades at the same size, and not between sizes.
| Bar designation | Grade 40 | Grade 60 | Grade 75 | Grade 80 | Grade 100 |
|---|---|---|---|---|---|
| #3 [#10] | 11% | 9% | 7% | 7% | 7% |
| #4, #5 [#13, #16] | 12% | 9% | 7% | 7% | 7% |
| #6 [#19] | 12% | 9% | 7% | 7% | 7% |
| #7, #8 [#22, #25] | — | 8% | 7% | 7% | 7% |
| #9, #10, #11 [#29, #32, #36] | — | 7% | 6% | 6% | 6% |
| #14, #18 [#43, #57] | — | 7% | 6% | 6% | 6% |
Swipe the table sideways on a phone.
Two things fall out of that table. The Grade 40 column stops at #6 — not because the values were left out, but because the bars do not exist (next section). And the floor drops as the bar gets bigger: 9% on #4 through #6 in Grade 60, 8% on #7 and #8, 7% on #9 and up. The 2020 edition adds #20 [64] to the last row with the same percentages; every other row is identical between the two printings.
Elongation is the ductility check, and it is the reason a higher grade is not simply better. Grade 40 stretches 12% before it breaks on a #4; Grade 80 stretches 7% on the same bar. Put the stronger bar in and the structure has less warning before it fails, which is the same point NOTE 1 makes about the tensile-to-yield ratio, measured a different way.
This is a footnote to Table 2 and it is a requirement, not a note: “Grade 40 [280] bars are furnished only in sizes 3 through 6 [10 through 19].” There is no #7, #8, #9, #10, #11, #14 or #18 Grade 40 bar in the standard. If a bar list asks for one, it is either a typo or a project specification that has to be resolved before steel is bought — the usual answer is Grade 60 at that size, and that changes the lap and the development length, not just the price.
Grade 40 is the grade A615 leaves unmarked, and the clause says it in one line: §19.3.4 gives a designation for 60, 75, 80 and 100, then closes with “No marking designation is required for Grade 40 [280] bars.” The sentence is identical in both printings — A615/A615M-12 §19.3.4 and A615/A615M-20 §19.3.4. The usual reading on a deformed bar is therefore that a mill mark, a size and an S with no number and no line is Grade 40 — but that is the absence of a mark rather than a mark, and a plain bar has to be tagged for grade instead. The full reading order of the marks is on what rebar is made of; this page only fixes which line count belongs to which grade.
Grade 60 is also called Grade 420, and 60,000 psi is 413.7 MPa — not 420. The bracketed values in the standard are a rounded designation series in steps of 10 MPa, not a conversion of the psi figure:
| Grade | psi | Exact MPa | Printed in the standard |
|---|---|---|---|
| Grade 40 [280] | 40 000 | 275.8 | 280 |
| Grade 60 [420] | 60 000 | 413.7 | 420 |
| Grade 75 [520] | 75 000 | 517.1 | 520 |
| Grade 80 [550] | 80 000 | 551.6 | 550 |
| Grade 100 [690] | 100 000 | 689.5 | 690 |
Swipe the table sideways on a phone.
The exact column is arithmetic — psi × 0.00689476 — and it is here to show that the printed column is not. Grade 80 is the one that rounds down, from 551.6 to 550. A bar sold as Grade 420 is not a bar that tested at 420 MPa; it is the metric name of Grade 60, whose floor is 413.7 MPa.
§19.3.5 turns that naming into a permission: a metric size bar of Grade 280 may be substituted for the corresponding inch-pound size bar of Grade 40, Grade 420 for Grade 60, Grade 550 for Grade 80, and Grade 690 for Grade 100 — the 2012 edition pairs 520 with Grade 75 instead of 690 with 100, because Grade 100 was not in it. The clause pairs a metric size bar with the corresponding inch-pound size bar, and the bracket in Table 2 is that size: #6 is #6 [19]. So it is an ordering permission between the two designations of the same bar, not a statement that Grade 280 steel is interchangeable with Grade 40 by strength.
§19.3.4 lets the grade be rolled as a number or as lines, and the count is fixed:
A mark is a grade mark, not a heat mark. It tells you the floor the bar was made to and nothing about what that heat actually tested at; the certificate carries the test results. And a line count on its own is not a grade until you know the mill’s symbol and the bar size, which is why the marks are read in order rather than one at a time.
Weight and area: nothing. A #5 is 1.043 lb/ft and 0.31 in² whether it is Grade 40 or Grade 100, because Table 1 is indexed by bar size alone. The rebar weight calculator and the rebar area table are grade-blind for that reason.
Development and lap length: everything. The ACI 318 expression on the development length page puts fy in the numerator, so the same bar size in Grade 80 has to develop a larger force over a longer embedment than in Grade 60. Upgrading the grade is not a way to shorten a lap; it lengthens one. The grade factor ψg in that same formula is 1.0 at Grade 60 and below, so the step above Grade 60 is where a detail that was copied from an older sheet quietly stops being conservative.
The specification itself. ASTM A615 is the general carbon-steel specification. A706 is the weldable and seismic one, and it carries only Grades 60 and 80 — which is also why §19.3.3 of A615 allows the SW mark on Grade 60 and Grade 80 bars only. The side-by-side of the two specifications is on the rebar size chart; the point here is that the grade list is not the same list in both.
It is a minimum yield strength, in ksi. Grade 60 means a yield strength of at least 60,000 psi (420 MPa), Grade 40 at least 40,000 psi (280 MPa). The grade is a floor for the lowest bar in the lot, not a measured value, and it says nothing about tensile strength, which is a separate and higher requirement in ASTM A615 Table 2.
90,000 psi (620 MPa) in the 2012 edition of ASTM A615 and 80,000 psi (550 MPa) in the 2020 edition. The yield is 60,000 psi in both. The number 60 in the grade name refers to the yield only, which is why a table that lists 60,000 psi as the tensile strength has read the column above it.
In yield, yes: 60,000 psi against 40,000 psi, and in tensile 90,000 against 60,000 psi under the 2012 edition or 80,000 against 60,000 under the 2020 edition. It is also less ductile, with a 9% elongation floor on #4 to #6 against 12% for Grade 40. Swapping one for the other changes lap and development length, so it is a design decision, not a like-for-like purchase.
No. The footnote to ASTM A615 Table 2 states that Grade 40 [280] bars are furnished only in sizes 3 through 6 [10 through 19]. There is no #7 or larger Grade 40 bar in the standard, so a bar list calling for one is either a typo or a project specification that has to be resolved before the steel is ordered.
Grade 100 [690] in the 2020 edition of ASTM A615: 100,000 psi yield and 115,000 psi tensile, with a tensile-to-yield ratio of 1.15 against 1.25 to 1.50 for the lower grades. It was introduced in the specification in 2015. Grade 75 [520] exists in the 2012 edition and is not in the 2020 edition, so the highest grade depends on which edition the project is specified to.
Yes. 420 is the metric designation of Grade 60, and the exact conversion of 60,000 psi is 413.7 MPa, so the printed 420 is a rounded name rather than a converted value. ASTM A615 §19.3.5 permits a metric size bar of Grade 420 to be substituted for the corresponding inch-pound size bar of Grade 60.
Count the grade mark: one line is Grade 60, two lines Grade 75, three lines Grade 80, four lines or the letter C is Grade 100, and no grade mark means Grade 40, which has no marking designation under §19.3.4. Read it together with the mill symbol, the bar size and the S or SW, since a line count alone does not identify the bar.
No. Weight per foot is set by bar size in ASTM A615 Table 1 and is identical for every grade: a #5 is 1.043 lb/ft as Grade 40, 60, 80 or 100. What the grade changes is the strength the bar develops, and therefore the lap and development length, not the weight, the area or the bar count.