What are the imperial/ASTM equivalents for metric fastener grades?

Both ASTM F568M and ISO 898-1 outline several grades of metric fastener, from low carbon/low strength, up to high strength/heat treated alloy grades. The equivalents listed below should be only considered as rough equivalents. Special care should be taken before substituting grades to make sure that an acceptable substitute is being used. For example, grade 8.8 has the same mechanical requirements all the way up to M80 (3-1/8”), however the ASTM equivalent, A449, lowers its mechanical requirements as the diameter increases, necessitating a conversation between the purchaser and manufacturer to decide the best way of satisfying the necessary mechanical requirements. Similarly, grade 12.9, where as common in metric circles, has as its only ASTM mechanical equivalent, A574. A574, however, is a socket head cap screw standard, so studs and hex bolts are left out and do not have a direct equivalent.

Portland Bolt is happy to help if you have specific questions or needs. We cannot manufacture metric sizes or bolts to metric grades, and we are not able to make recommendations, but we can work with you to determine what is feasible and cost effective if a substitution is allowed.

As always, an engineer should be consulted before grade substitutions are made.

Diameter Range Metric Grade Approximate ASTM Equivalent Description Tensile, min Yield, min
Mpa ksi Mpa ksi
All 4.6 A307A Low or medium carbon steel 400 58 240 35
through 1" (M24) 5.8 - Cold worked low or medium carbon steel 520 75 420 61
through 1" (M24) 8.8 A449 / F3125 Grade A325 Heat treated medium carbon steel 830 120 660 96
above 1" (M24) 8.8 A193B7/A354BC or F1554G105 Heat treated medium carbon steel 830 120 660 96
through 1-1/2" (M36) 8.8.3 A325 Type 3 / A449 Type 3 Heat treated medium carbon weathering steel 830 120 660 96
All 10.9 A490/A354BD Heat treated medium carbon alloy steel 1040 151 940 136
through 1-1/2" (M36) 10.9.3 A490 Type 3 Heat treated medium carbon alloy weathering steel 1040 151 940 136
All 12.9 A574 Heat treated alloy steel 1220 177 1100 160
Written ,


    @Nikul- Apologies but we don’t currently make any metric-graded product so we do not know what is commonly used for that grade.

    Hi Dane

    As I understand it, the mechanical properties of A193B7 are achieved from the heat treatment of materials such as SAE 4140 which is an alloy steel, however in the table you indicate that ASTM A193b7 is a medium carbon steel with heat treatment. Is this correct?

    @Franco- We can see where that could be confusing. What we were trying to say is that metric 8.8 is a medium carbon steel. However, due to differences in the metric and imperial standards, A193 B7/A354 BC is a closer match to mechanical properties in larger diameters than A449.

    @Kamlesh- Apologies, but we do not have a conversion chart for ASTM to EN grades, other than what is listed above.

    @Saif- Those two bolts have many similarities, but they are not identical. We are not able to make any substitution recommendations, you will need to contact the project engineer in order to approve any substitutions.

    @Hermant- Apologies, but we are not familiar with LA 8740 bolts. If you had more information, we would be happy to look into it.

    @Hilmi- threads can be produced by either method, so you will need to check with your supplier and find out how they are producing theirs. If we were to manufacture a bolt of that size (albeit in an imperial equivalent size), we would cut thread them.

    According to ASTM A163 GradeB7 (ASTM F1554 Grade 105) minimum specified yield strength 0.2 percent offset, fya is 105,000 psi (724 Mpa) and for ISO 898-1 Class 8.8. has 92,800 psi (640Mpa). Can you still please confirm equivalence betwen ASTM A163 GradeB7 (ASTM F1554 Grade 105) and ISO 898-1 Class 8.8 (Source ICC-ES Report ESR-3187 Table 3). Thank you!

    @Milos- We can confirm that the two grades (ASTM A193 B7 and ISO 898-1 Gr.8.8) share many similarities, and in many cases can be substituted for one another. We cannot say however, that they are exactly equivalent, only similar.

    @Heinrich- Apologies, we do not stock any 10.9 or standard Caterpillar bolts. We specialize in custom construction anchor bolt. We can make specials for the OEM industry, and would be happy to quote if you are needing something non-standard, but it isn’t our primary niche.

    Hi Dane

    Is an ISO 898-1 grade 5.6 equivalent to ASTM 307 Grade B?
    I’ve noticed in the above table 5.6 is not mentioned (either 4.6 or 5.8)
    Thanks in advance!

    @Alejandro- ISO 898-1 class 5.6 is a valid property class. It appears to be very similar to 5.8, but with slight variations in the required chemistry and mechanicals. It also requires a charpy impact test. We would say that it is similar to A307B in that it is mild steel and lower in strength, but it is not an identical crossover.

    Good Morning,

    I was asked to use a DIN931 – M20X90-10.9D1G bolt. Would an A325 Galv Assembly be comparable (I know I would have to get approval from my engineer but metric is proving to be difficult to find).


    @James- Grade 10.9 is a slightly higher strength fastener than ASTM A325 (approximately 150ksi vs 120ksi tensile), and will have slightly different dimensions(head size, thread length). It is certainly possible that an A325 will work in your application, but you are correct in needing an engineer to approve that kind of substitution.

    @Soebroto- We don’t think that a B7 bolt is as strong as a 12.9 bolt, so you would need to have that substitution approved by the project engineer.

    @Mashkoor- An A490M bolt is a male threaded heavy hex structural bolt, whereas the A563 10S is the female threaded heavy hex nut used with the aforementioned bolt.

    Greetings to ALL,

    My black finished 10.9 grade nut and bolts are getting rusty. How can I avoid it as I cant do hot dip galvanization due to Hydrogen embritlement according to ASTM F 568 Section 4.6 and Note 1.

    @Asad- You are correct that caution should be used when galvanizing 10.9 bolts. There are several other coating options; zinc, Geomet, or other various proprietary coatings that are alternatives to hot dip galvanizing. F568M, which is no longer in use, does not prohibit other coatings. ISO 898-1 is the current standard for metric 10.9, 8.8, 12.9 etc grades, and it may have different coating guidelines, but we are not as familiar with the ISO standard, so are unable to discuss thoroughly.

    Is it permissible (by Code) to reuse previously torqued (torqued to specification) ASTM325, ASTM325M and Grade 8.8 bolts

    Is it possible to use bolt classe 8.8 instead of A325 and A307, if ok , could you please confirm that they have the same chemical properties ( to avoid corrosion)

    In order to substitute, you’d need approval from the project engineer. 8.8 bolts should have similar chemistry as A325 bolts (although not identical), but both will be quite different than an A307 bolt. None of the three will have any inherent corrosion resistance unless you choose to coat them.

    @Tom- Any material substitutions should be approved by the project engineer. That said, A490 bolts and 10.9 bolts have very similar mechanical requirements, so if the dimensional differences of the A490 do not cause any concern, we also see no major concern.

    @Ashraf- A193 B7 is mechanically similar to 8.8, but can vary chemically. We do not see an issue in replacing 8.8 with B7, but as always, the project engineer should approve any substitution.

    Hello Dave.
    What is the advantage of using bolts 8.8 coated with hot dipped galvanized and Dacromet?
    Which process would hydrogen embrittlement be the most affected.
    We want to use these bolts for structural steel bases.


    @George – 8.8 bolts are heat treated and high strength, but not high enough strength that they are susceptible to hydrogen embrittlement. They can be hot dip galvanized without embrittlement issues. Dacromet is also allowed, but it is being discontinued due to ROHS concerns.

    @Hareshchandra – We are not very familiar with ISO 898, but we do believe there are many grades (4.6, 8.8, 10.9, 12.9 etc) within that standard with have rough, but not exact equivalents to ASTM standards. We’d be happy to talk you through the specifics of whichever grade you are working with if you’d like to contact us through either this website, email, phone, or live chat.

    for A307A how its measurement mention in MTC ..? in inch or Metric ,why..?
    suppose if mention in metric(eg:M12x100) in mtc its is acceptable..? please replay

    @Nisa- We are sorry, but are unsure of what you are asking. We sell and can manufacture inch-dimensioned products. We do not handle metrics nor do we know much about them.


    Can you please advise for below alternative Bolts/Nuts material. Application is Deaerator Columns, for bolting Columns to module structure:

    1. ASTM A325M T-1 in place of Gr. 8.8 for Bolts
    2. A194 Gr 2H in place of ASTM A563 Gr. DH for Nuts

    @Bilal- For the bolts, those grades are very similar from a chemical and mechanical standpoint, but any substitution should approved by the project engineer as there are subtle differences between the two. For the nuts, A194 2H is an allowable substitution per ASTM.

    is it possible to use 10.9 as equivalent to a193 b7?
    as I know, A193 B7 bolt is low alloy steel fit to high temprature service up to around 400 C, while all bolts manufactured to iso 898 (such like 10.9) is normally applicable to be used only under 150 C.
    So Im worry that 10.9 cannot replace B7 bolt in high temprature service.

    @Abdelaziz- You are correct, 10.9 should not be substituted for A193 B7 without an engineer’s approval. B7 is formulated for high temperature applications, whereas 10.9 is for general purpose use.

    is that ok to use material C1015 to produce the item which requires grade 5.8?
    kindly ask you to reply, thank you

    @Leon- As long as the C1015 material you chose to use meets the mechanical and chemical requirements of 5.8, then you can use it. C1015 is typically furnished as chemicals only, so you may need to test it to assure the proper mechanical requirements are met.

    @Remis- You would need to have that substitution approved by the project engineer. There are similarities between those bolts, but some differences as well.

    Yes, it can be substituted each other (ASTM A325M bolt is equivalent to the properties of an ASTM F568 Class 8.8 (ISO 898/I) And please refer to Section 4.1 of ASTM A325M.

    Hello Dane, Could you please help me. Can a Grade 8.8 foundation bolt be used at minus 25 Centigrade. Many thanks in advance, regards, David.

    @David- We don’t have a lot of experience with 8.8 bolts, so we are not sure how they would perform in cold temperatures. A charpy test would tell you if the 8.8 bolts maintain their ductility at cold temperatures.

    @Prashun- Apologies, but we are not familiar enough with all the various ISO standards to know which grade is the closest equivalent.

    @Eman- Apologies but we are not familiar enough with ISO fastener standards to know what the equivalent would be.

    @KK-No, A193 B7 is a high strength bolting material designed for high temperature, high pressure applications. Grade 8.8 is a medium strength bolt for general purpose applications. They should not be substituted without approval from the project engineer.

    Hi Dane ,

    Are you the contact person for your company ? I have sent a no. of enquiry but no reply at all. Kindly advise contact details. Thank you.

    Dear Dane,
    Please advise. Are there any advantages (or disadvantages) in using structural bolt A325 in mm instead of in inch (for example M16 vs 5/8″ bolt) ?
    Thank you and Regards,

    @Dinar- As long as the bolt meets the requirements of the application, and fits in the hole, you should be able to use either metric or imperial fasteners depending on which is more readily available.

    thank u mr. McKinnon for sharing the valuable information with us…… I just want to know the Metric Equivalent for Heavy He bolt conforming to ASTM A-307, Grade B standard please…
    Thank u

    Do you have the following info for metric grade 5.8: Enlong % min, RA % min and Hardness Rockwell min and max.

    @David- It does not appear that class 5.8 fasteners have any requirement for elongation or reduction of area %. The minimum hardness is 82 HRB.

    @Niels- Yes, A574 screws have a specified minimum tensile strength of 170-180ksi (depending on diameter), and the threshold for hydrogen embrittlement concerns is 150ksi.


    Could you please give me the equivalent din material number for ASTM F 1554 Grade 36- 55-105 ?


    what is the equivalent ASTM bolt for DIN-933 and DIN-6914. is it possible to change A325 and A490 bolts with these DIN Bolts. is there reference for the same.

    @Ranjith- Thank you for your question, but we are unfamiliar with the DIN standards, so cannot help in this case. Apologies.

    First off thank you for all the technical information Portland Bolt has brought together and made available to the public. I find myself here almost every work day.

    Is it acceptable to use the A193 GR B8 and B8M as a rough equivalent for metric 304 and 316 stainless steel bolts? Also, does the A449 have to be used or is it acceptable to use SAE J429 Gr 5 as a material specification for plain carbon steel metric bolts. I just want to avoid creating issues for our procurement team by using the wrong spec?

    @Michael- B8 and B8M is 304 and 316, respectively. As long as you convert the diameter units, using B8/B8M should be fine. As for A449/gr.5, neither will be available (as far as I know) in metric. The approximate metric equivalent to A449/gr.5 is ISO 898 gr.8.8. Those should be pretty easily obtainable.

    We want to go for Anchor bolts with SI system. For that i found A563M-04 for Nuts, F436M-93 for washers, but F1554 for anchor bolts is available only with FPS system. What shall be refered for its SI equivalent. I failed to found it. Requested to give your openion.

    @Vasant – I am not aware of any direct metric equivalent for F1554. That said, if you can find a manufacturer who can manufacture to metric dimensions, there is no reason they cannot just make bolts to meet the chemical and mechanical requirements of F1554, but with metric dimensions.

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