How do I determine the yield and tensile strength of a specific diameter of bolt?

In most cases, the strength of a given material used to make a fastener has strength requirements or parameters described as pounds per square inch (psi) or thousands of pounds per square inch (ksi). This is helpful when analyzing what grade of material should be used for a given application, but this doesn’t tell us the actual strength of that diameter of material. In order to calculate the actual strength values of a given diameter, you would use the following formulas:

Note: the formulas below do not depend on the finish of the fastener.

Yield Strength

y * a = s

Take the minimum yield in psi of the ASTM grade (see our Strength Requirements by Grade Chart for this value), multiplied by the stress area of the specific diameter (see our Thread Pitch Chart). This formula will give you the ultimate yield strength of that size and grade of bolt.

Example: What is the ultimate yield strength of a 3/4″ diameter F1554 Grade 36 rod?

36,000 psi * 0.334 in^2 = 12,024 lbs
This is the minimum requirement for F1554 grade 36. In other words, a 3/4″ diameter F1554 grade 36 anchor rod will be able to withstand 12,024 pounds force (lbf) without yielding.

Ultimate Tensile Strength

y * a = s

Take the minimum tensile strength in psi of the ASTM grade, multiplied by the stress area of the diameter. This formula will give you the ultimate tensile strength of that size and grade of bolt.

Example: What is the ultimate tensile strength of a 3/4″ diameter F1554 Grade 36 rod?

58,000 psi * 0.334 in^2 = 19,372 lbs
This is the minimum requirement for F1554 grade 36. In other words, a 3/4″ diameter F1554 grade 36 anchor rod will be able to withstand 19,372 pounds force (lbf) without breaking.

Shear Strength

First, find the ultimate tensile strength using the formula above. Take that value and multiply it by 60% (0.60). It is important to understand that this value is only an estimate. Unlike tensile and yield strengths, there are no published shear strength values or requirements for ASTM specifications. The Industrial Fastener Institute (Inch Fastener Standards, 7th ed. 2003. B-8) states that shear strength is approximately 60% of the minimum tensile strength. For more information, please see our FAQ on bolt shear strength considerations.

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157 comments

    Hello.

    I wanted to know that for Tensile Strength Testing, what is the minimum length of the bolt that can be used?
    Is it possible to test on a 25 or 30mm long Bolt, or we need a minimum length of 190-200 mm?

    Thanks, in advance.

    @Hiren- the minimum test sample length will be determined by the type of testing equipment available. There are specialized machines that are able to test very small pieces, and others like ours that require a minimum of about 6 inches/150mm.

    Hi

    I would like to have stainless grades and their properties table. Is there any website of PDF ?

    Thank

    I just want to know that how i calculate the strength of 12 mm hexagon bolts, for example, in one rack 08 bolts of 12 mm hold the rack, than how much weight capacity of the rack.

    @Mehmood- If you know the tensile strength of your fasteners, you can multiply it by the tensile stress areas of the threads, that will give you the minimum breaking strength of your bolt. You can also calculate shear by multiplying the tensile value by 60%.

    I need to figure out the sheer strength of a 3/8-16 zinc plated u-bolt. The formulas on your website require that know the type of steel alloy the bolt is made out of. How do I find that information? What is the tensile strength in psi of the weakest steel alloy commonly on the market? Thank you!

    @E- Most mass produced items like that are made from low carbon steel wire. The lowest grades commonly have a tensile of about 60ksi, and whereas we can’t promise that yours will be in that range, we’d be surprised if it was much different.

    @Ade- We are sorry, but we are not familiar with BS3692, so are unable to be 100% certain. However, in ISO 898-1, which we believe BS3692 is based on, the yield strength for 8.8 is 640 MPa.

    The information on the bolt head is the strength specification. If the grading is 8.8, with reference to the first number 8, this means the ultimate tensile strength (breaking strain to be at least this) is 800MPa, or, 800N/mm². With reference to the second number, multiplied by 10, gives the percentage of the first calculation to provide the Yield Strength. The yield strength defined as the tension required to stretch the bolt beyond its elastic capability to 0.2% plastic deformation. The Proof strength is usually around 90% of the Yield strength for standard steel bolts. (Not Stainless). Be careful when calculating as the threaded section of a bolt has a smaller cross-sectional area than the smooth shank, for instance, the smooth shank of an M16 bolt has a cross sectional area of 201mm² wheras the threaded part has a defined area of 157mm².

    Hi All,

    Im looking for a table that will tell me the shear and tensile capabilities of various size bolts. Can anyone point me in the right direction?

    Maybe there is a decent book that I can purchase with this information?

    Thanks in advance

    @Nick- The AISC Steel Construction Manual has that information in various charts. It is available for purchase through the AISC website.

    Dear Sir
    First of all, I appreciate your generosity and answering the questions. I am a student and I strictly need the stress-strain chart for ASTM A574 Hex Headed Bolts (M30).
    I am waiting for your kind response
    Arash

    @Arash- Thank you for your interest, but we do not manufacture A574 cap screws, and so therefore we do not have a stress-strain curve to share. Apologies.

    6 Ton Lifeboat hook will be installed to anchor bracket with 42 mm anchor bolt. Material of the hook is duplex stainless steel, factor of safety is 6 : 1

    Please advise minimum length of material required below the hole and beside the hole.

    Thank you for your time.

    @Raghu- We are sorry, but we do not have any engineers on staff and so are unable to provide those calculations.

    @Kandyice- We are unsure of what you are asking. If you calculate the yield at 100%, can you not just multiply that by 70% or 40%, or are you asking something different?

    Hi

    For an M6 and M8 bolt I need to determine the bolt length to withstand certain applied forces.

    How do I determine what length bolt to use?

    Thanks
    Ahmed

    @Ahmed- You would need to consult an engineer familiar with the project in order to determine that. We can assist with specific questions about the bolt once you determine what you need, but we are unable to make engineering recommendations.

    @Ng- We have tables and formulas for smaller bolts, but nothing with metric grades or sizes since we do not manufacture anything in metric sizes or grades. Apologies.

    I am happy to contact my members here. A concrete slab was casted over 9m span beam, and later it was found the slab projection of 0.8m long with ~5m width was required to rest the window components. I don’t want to disturb the beam and slab by chipping of the concrete as the span is quite long and it is critical. In this regard, I am deciding to use square pipe 150x75x6.3mm to hold the load coming over this projected structure by bolting pipes on concrete slab to avoid the distressing of structure in place. In addition, I have calculated the load coming on to this projected portion but I am not sure how to design the number of bolts and dia bolts to counter act the load on the projected portion. Basically, the load is acting to the projected pipes as cantilever load. I wanted to know the how to get the economical section of the pipe and the bolt detail to service the load.

    @Lachu- Apologies, but we do not have any engineers on staff and so are unable to make any recommendations in this instance. We are happy to answer whatever questions you may have once you have determined what size, grade, and quantity of bolts you need.

    @Muhammad- Apologies, but we do not have any experience with sheet metal, and do not know how the mechanicals are tested or calculated.

    Does strength of an all thread change if you band saw/ cut to a shorter length. If so what calculation do you use to gather that information?
    Thanks

    @David- No, as long as you do not use heat (like a cutting torch) to cut the bolt, the mechanical properties should not be altered.

    Are there industry standards in hardness (Rockwell) for specific grades of bolts (primarily metric) – what would a failed hardness test indicate in a bolts tensile strength?

    In example, 12.9 rated bolt, industry standard reads 44-49 HRC. Bolts test out at 84-89 HRB. Would this be an indication of poor quality control during production? Suggestions on 3rd party laboratory testing facilities?

    Sorry error on actual hardness tested.

    @Jerod- 84-89 HRB hardness readings would indicate a strength close to mild, low carbon steel (grade 2, 4.6, A307). If your 12.9 bolts have readings that low, there had to be an error in either the manufacturing processes or in the testing procedures. 12.9 bolts should never be anywhere near that soft. We use IMR Test Labs here in Portland often, and I believe they have facilitates elsewhere as well.

    Hi Dane,

    In ACI318-14 clause 17.2.3.4.3 there is term: NOMINAL STEEL STRENGTH of anchor, I was wondering is this same as Yield Strength you defined above? otherwise please clarify.

    Thanks,
    Mark

    @Mark- Nominal steel strength is not necessarily an exact equivalent of yield. I was not able to find an exact definition in ACI318, but sections 4 through 6 in appendix D discuss steel strengths in detail.

    I am currently working on a project that involves the use of a hydraulic torque wrench to tighten a series of nuts on an oil field blow out preventer or otherwise known as a B.O.P. So what I need to know is how many foot pounds of torque would be required to tighten these heavy hex nuts. Therefore here are the figures:

    Torque tool generates up to 10,000 PSI of hydraulic pressure at testing or proving.
    Stud size is 1 7/8″
    Nut size is 2 15/16″ heavy hex
    Threads per inch are 8
    Material choice would be ASTM A193 B7 or B8

    Note:
    Hydraulic torque wrench would be as manufactured by companies like Titan Technologies, Hytorc, Wren etc.

    If you need further information I can supply it.

    Best regards and Merry Christmas

    @Mario- It is difficult for us to make specific torque recommendations because every application is different and because torque is a tricky animal. What we’d need to know first is what tension or clamping force are you trying to achieve? We can then calculate a ballpark torque value, but you would still want to verify that before installation.

    hi , i have shaft clamped by bolt. i need to calculate the load coming on bolt when i apply torque on shaft of 200 Nm.

    @oyewole- 58,000psi is the minimum tensile strength of A36 and F1554g36 material. You multiply that by 0.334 in2 which is the area of the minor diameter of the threads for 3/4-10. That gives you the minimum ultimate breaking strength of 3/4″ A36/F1554g36.

    Hello I was looking to write a test method validation for an elongation test which will be in compliance with the EN 45502-2-3 clause 23.3. Can you tell me how can I do that ?

    How to calculation torque value on stud bolt3/4×150mm flange 3″×300# gasket 3″×300.please show me how to calculate

    @Zulkifly- The torque equation, T=KDP is on our torque page along with common values. However, with the addition of a compressible gasket, we can’t be sure if those charts apply as they are for steel to steel connections only.

    General question is tensile strength rated for the bolt being loaded and torqued? Does tensile strength fall off if the bolt is loose, but still has thread engagement with the nut?

    @Brad- The tensile strength of the bolt does not change if it is loose, as long as it is still engaged in the nut at least one diameter. If it is engaged less, then it is possible that the assembly will fail (probably through nut stripping) before the ultimate tensile is achieved.

    I’m looking for a bolt or rod to be used as an axle for a physics science project. 24″ in length, capable of handling 500 lbs static load and approximately 10,000 lbs dynamic load.

    @Brian- We are able to make many grades and diameters of bolt or rod, but we don’t have any engineers on staff, so we would be unable to recommend any thing specific. You would need to tell us what diameter and grade to fabricate.

    how do i need to calculate the tensile strength for the self drilling screw? Is there have any industries standard value for the tensile strength of self drilling screw? The self drilling screw based on SCREW #8 x 1/2(P/H).

    @Rezza- we are sorry, but we do not have any information about self drilling screws. We primarily handle larger, custom anchor bolts.

    Is it possible to estimate the effects of torsion (torque) on a bolt in relation to its yield and tensile strength? Thank you.

    @Andy- We are not certain what exactly you are asking. We can calculate the torque needed to achieve a specific load, but the effects of torsion on yield? We are not sure.

    For SA193 B7 bolt of 3/4inch diameter, the allowable Stress at 500F are 25000psi and what torque value should be considered for a Flexotelic Gasket

    @Kamlesh- I am sorry, but are not able to make recommendations for specific applications like this. Apologies.

    As I understand it, in simplist terms, tensile strength is the force required to pull a bolt apart and yeild is the force required to deform it to the point where it does not fully recover. On metric bolts it is listed as a percentage of tensile strength 8.8 is 800 megapascals with 80% yield strength or 640 megapascals. I was wondering how the tensilestrength of the bolt related to the thread strength. I never realized that the bolt would fail before the thread, with sufficient engagement and a female thread of equal strength. How badly does a full thread bolt affect shear strength when it is used in place of a partial thread bolt where the unthreaded part was in the stress or shear area? Thanks, Jeff

    @Jeff- Yes, the bolt will always fail in tensile as opposed to thread stripping, unless there is a problem like loose threads or weak female material. As for shear, the strength in the threads is approximately 25-30% less than the shear strength in the shank. That is simply due to the minor (root) diameter of the threads vs the full diameter of the shank.

    Slow down there, Dane, you should qualify that “the bolt will always fail in tensile as opposed to thread stripping” statement. The thread will *absolutely* fail if improperly designed or installed. The good news is that it is difficult to imagine a thread failure on a bolt and nut connection, but you should still check that it is installed properly for the anticipated loads, and make sure the assembly doesn’t pull out of the connection material. What i mean is (and this is an unrealistic and exaggerated example), imagine 1/2 inch bolts/nuts bolting into aluminum siding panels – unless you have large washers, the bolts can be pulled right out of the siding. Of course, the siding would likely pull away from the house first, but…

    If they think carefully, a competent person can figure out what will work. When in doubt, call an engineer. You may be surprised how willing they would be to work with you, especially if it is an interesting project. If you’re building a structure that could collapse on someone, *always* get a structural engineer to design it.

    @Chris- You are correct, I should have qualified that if the bolt is improperly designed or installed, it could strip. I will edit. Thanks for the catch.

    I would assume that when quantifying strength of any structural component that it is implied that it is assembled properly. Of course there is possibility of failure if all is not right. To require stipulation that it must be installed properly is silly. Anyone with the competence to calculate tensile strength would already know this.

    I’m attempting to find the maximum weight an 1144 steel rod can hold at both ends, though I’m not sure which type of equation to use.

    Essentially, I am making a barbell, and will have weight plates on both ends of the bar. I, of course, will be gripping the bar with both hands, but would like to know what the possible breaking point may be if I only had one lever/one hand on the bar.

    Thanks

    @Z- We can calculate the tensile, yield, or shear strength, but to me it sounds like you’d be more concerned with the bar bending. If that is the case, we do not have that equation. We also would need to know the condition of the bar – that is if it was cold drawn, and if so, whether it was a normal draft or heavy draft as that can effect the strength of the bar. For an example, let’s use normal draft. The tensile of the bar would be 60,600lbs. The yield would be 54,500lbs, and the shear would be 36,360lbs. Again, for a bending moment or other calculation, you’ll need to find someone with that equation.

    or, you could just go to a sporting goods store and see what their bars are made of and the dimensions.

    you’re looking for allowable plastic deformation values, which will depend on bar diameter, length and material strength. You want the bar to be able to bend (so you can still pick it up), but not bend permanently. Difficult to imagine that you’d be able to break or bend a bar made of appropriate material, but you may be the Hulk! This stuff is covered in a subject called “statics” or “static design”: https://www.engineeringtoolbox.com/statics-t_63.html

    How can I calculate the thread strength depending of the length of engagement of a bolt in a metal plate? More precisely, I want to ensure that a 3/4-10 bolt won’t shear out the threads of the 1in thick plate in wich it is screwed. The plate material tensile strengths are :
    Ultimate : 78ksi
    Yield : 44ksi
    Also the shear modulus is 11600ksi.

    @Samuel- I am not sure how to calculate that, but what I can tell you is that, beyond a certain point, additional thread engagement does not add any more strength, only cost. The first three or four threads shoulder the lion’s share of the burden, then it diminishes beyond that. Rule of thumb is that one diameter’s worth of thread engagement is sufficient, so a 1″ engagement on a 3/4-10 bolt should be more than enough.

    These are such interesting questions! Yes that is a good analysis and rule of thumb on thread engagement. That configuration should be able to carry a hefty static tension load. If it is a large swinging or bouncing load, get an engineer to look at it.

    How can I calculate the breaking point ( The max weight load when it breaks) of an all thread with the length of 6″.

    @Chano- In a straight line pull, the length of the bolt is irrelevant. The breaking point is the tensile stress area multiplied by the minimum tensile in psi. If your joint is more complicated, and if there are forces that are not in a straight line, then you will need to consult an engineer.

    How do I determine the yield and tensile strength for a specific diameter of a 1100 aluminum stud?

    @Frederick- You would multiply the tensile stress area of the stud by the yield and tensile in psi of the aluminum. We, however, do not have any strength information about 1100 aluminum.

    Hello I am seeking the tensile strength of a 1 inch thick a36 steel bar with a 1 inch hole threaded for national coarse thread. I want to know the tensile strength of the threads in the steel. Also I would like to know the same exact thing but for a 2 inch bar of the same steel. Please help I can not find anywhere.

    @Kelly- This FAQ shows you how to calculate the strength of both bars, however we do not know how the addition of that hole will effect the mechanicals. It will likely be determined by the location of the hole relative to the placement of the nut.

    @Aman- In order to help you with this question, we would need to know the grade of bolt and nut, as well as how the fastener is being used. For example do you need it’s tensile value, or shear value, or perhaps some other value?

    If a 1/4-20 x 5′ threaded rod falls a distance of 3′ to an uncarpeted shop floor, and there is no one in the building, will it make a sound? Thanks in advance.

    Hi, I have been trying to find a comparison chart to determine at what torque in NM a bolt would go into yield in this case a M20x2.5 A4-80 stainless bolt. any ideas?

    @Success- Each individual manufacturer of eye bolts has a chart that lists what their bolts are rated at. You will need to contact the manufacturer of your specific eye bolt to obtain that information.

    Hi, I’m building a barbed wire fence roller and would like to use 3/4″ 1018 cold roll round stock for the shaft that the wire spool will attach to. The shaft will extend beyond a pillow block bearing approximately 13″ and will not be supported on the end. The wire spool is approximately 12″ in length and has a 1″ O.D. Steel tube between the spool ends. This 1″ tube has an I..D. a little larger than 3/4″ which will allow the wire spool to slip over the 3/4″ inch shaft. I need to know how much pull weight can be placed on the shaft before it will bend. Thanks in advance.