Bolt Shear Strength Chart: Capacity Table (Free PDF)

From here all the rest of these charts are built.

So from this chart what you do is locate the class of property or grade of bolt you want to use in the left hand column and then locate the minimum UTS (ultimate tensile strength) for it in either ksi or MPa. Next look over to the rightmost pair of columns and locate the approximate ultimate shear stress for that material. Multiply the shear stress times the cross-sectional area of the bolt within the shear plane and you will get the load at which one bolt should of expected to shear off.

So let me just say out loud that there’s a 0.6 factor here. There are no shear requirements published by any standard (e.g., SAE J429, ISO 898-1) for fasteners; only tensile and proof requirements is published.

Engineering practice, including the Industrial Fasteners Institute guidance, FED-STD-H28 thread calculations, and Machinery’s Handbook, assumes an ultimate shear strength equal to about 60 percent of ultimate tensile strength. However, this is treated as an approximate value reflecting distortion-energy theory applied to ductile metals (yield = 0.577). Typical test results for fastener steels range from 0.57 up to 0.65. So 0.6 is simply the round-number approximation used; it is not a certain property.

The Min UTS columns (both sets of units) represent the minimum ultimate tensile stress required by each specification. Notice how they are broken into two rows? Above M16, class 8.8 increase from 800 MPa to 830 MPa, while SAE Grade 5 decreases from 120 ksi to 105 ksi above 1 inch, and Grade 2 decreases from 74 ksi to 60 ksi above 3/4 inch.

The single most common error people make reading the chart is using small bolt size for a larger bolt or vice versa.

The approximate shear strength columns are just the UTS in both units multiplied by 0.6. This is an ultimate stress, where the bolt splits apart. There is no safety factor included. Normally in machine design we divide by 2 to 3 for static loads and even higher when there is vibration, shock or fatigue involved.

Note this is an approximation. It doesn't apply to brass and aluminium fasteners. For those, the shear ratio is actualy closer to 0.65 to 0.7 and 0.55 respectively depending on the alloy.

Nor does it apply to structural connection design, where the 0.6 rule is replaced with calibrated design factors in codes such as AISC 360 and EN 1993-1-8. For these applications you can refer to their tabulated values below:

The stainless grades shown are included here, but the same applies to other ductile alloy and carbon steel fasteners. This excludes brittle materials like cast iron and some hardened screws above HRC 45, as well as aluminum, brass, or structural connection design.

In the left-hand column, find your coarse pitch and bolt size. In the right-hand column, find the worst-case ultimate single shear load for your property class. Use pounds-force (lb) or kN.

That’s a worst case. The bolt is assumed to be sliced through at its threaded section by the joint. This means the load are carried by the reduced tensile stress area, As, in the second column.

However, if the smooth shank sits in the joint line, then the bolt is 20 to 40 percent stronger. For this latter case you can see the shear plane comparison table below.

This means that each value is calculated as As x 0.6 x (minimum ultimate tensile strength). This is per ISO 898-1. For class 8.8, minimum UTS is 800 MPa through size M16; 830 MPa for size M18 and above. Class 10.9 has a minimum UTS of 1040 MPa. Class 12.9: 1220 MPa at all sizes.

Some chart references we’ve seen quote the nominal UTS of 800/1000/1200 MPa rather than the standard minimum. That is where some of the difference can be found. You will find an M20 class 8.8 quoted elsewhere at around 118 kN where here it is 122 kN. Additionally, 10.9 values are about 4 percent below our values. Both are correct. We’re following the tested minima stated in the standard.

In the two units, these numbers represents the same load in the kN and lbf columns. 1 kN = 224.8 lbf

These are ULTIMATE failure loads (no safety factor). Common machine design practice is to divide by at least 2 to 3 for a static working load.

Larger margins are needed if there is vibration, impact or fatigue on bolted joints. A proper joint analysis should be done with friction and preload consider.

Watch out for two traps. This table is for course pitch threads. Fine pitch threads has a slightly larger stress area. An M12 x 1.25 has 92.1 mm2 compared with 84.3 mm2 coarse. So the fine thread bolts is a bit stronger when sheared at the thread plane. If you want the number, scale by the area ratio.

Below M5, class markings aren't common. From M5 up, ISO 898-1 only assigns grades of 8.8 and 10.9. From M1.6 it assigns 12.9. For reference, I used the same stresses to compute the numbers for M3 to M4 rows. Often small screws is not marked. Before trusting them, check their true grade.

This is NOT a table for structural steelwork connections. Design codes apply their own shear coefficients and partial safety factors. For that see the table below from EN 1993-1-8.

Nor is it to be used for aluminium, brass or stainless fasteners. These have different strengths.

Also bear in mind that with a well-preloaded joint, service shear is transferred by friction between two plate. The bolt shank is simply the fail-safe.

In the chart above, locate your nominal bolt diameter in the left-hand colum. Select either a fine (UNF) or coarse (UNC) thread type. The numbers shows the ultimate single shear load in pounds-force for Grade 5 or Grade 8 SAE J429 bolts.

This assumes the threads are located in the shear plane. That means the tensile stress area (As) of the bolt take up the load. However, if the shear plane go through the smooth part of the shank then the capacity increase by approximately the ratio of shank to thread areas. For most sizes this amounts to an approximate 25 to 40 percent increase.

The TPI (threads per inch) are listed by series in the TPI column.

The corresponding tensile stress areas follows ASME B1.1 and FED-STD-H28 practices and are listed in the As colum.

As stated above, fine threads has a shallower profile and thus a larger stress area. At the same nominal thread size, this provide approximately 5 to 15 percent greater shear capacity. For example, 1/2-20 UNF Grade 8 has 14,391 lbf compared to 12,771 lbf for 1/2-13 UNC Grade 8.

They calculate their loads as As times 0.6 times the minimum ultimate tensile strength (UTS). For sizes through 1 inch, Grade 5 is rated at minimum UTS 120,000 psi. But then the rating go down to 105,000 psi for sizes between 1 1/8 and 1 1/2 inch. Don't extrapolate on those smaller size values upwards because the step occur in the middle of the rows.

Grade 8 carries 150,000 psi over all its range from 1/4 inch to 1 1/2 inch. Note that the table end at 1 1/2 inch because SAE J429 does likewise. For larger imperial bolts, look to the various ASTM specs such as A193, A307 and A354.

These are ultimate failure loads without any safety factor considered. No allowance is made for fatigue, bending, or prying. For ordinary static working loads you should of divide by 2 to 3.

Remember, Grade 2 hardware store bolts top out at roughly half the Grade 5 numbers. Grade 2 has a UTS of 74,000 psi up to 3/4 inch and 60,000 psi above that. Don’t make the mistake of substituting an unmarked bolt where I used a Grade 5 or 8 fastener based off this chart. The grade will be marked on the head. A Grade 5 has three radial dashes while a Grade 8 has six.

Note that this is not for AISC 360 governed structural steel connections. For those, there’s a separate table with resistance factors and Fnv stress calibrations.

Nor should you use it if your bolts are nonferrous or stainless. Same goes for threaded rod without a known grade. If you have a datasheet for the particular fastener, follow that; a derived table doesn't trumps it.

The table above illustrate the added strength (or loss of strength) based off the location of the shear plane relative to the bolt. For each shear case, there are four load columns corresponding to single shear through the full shank, single shear through the thread portion only, and the same cases in double shear. The numbers shown are ultimate loads for a class 8.8 bolt, with multipliers for 10.9 and 12.9 indicated in the note. Since the shear plane geometry are independent of grade, these multipliers are exact.

The smaller tensile stress area is the threaded section, and the shank area column is the entire cross-sectional area of the unthreaded body (pi/4 x d2).

The fourth column’s ratio demonstrate the price you pay when you allow your threads to be on the joint line. This results in a loss of 20 to 28 percent of shear capacity for a typical metric bolt. For this reason, structural codes prints special reduced values when threads is in the shear plane, and AISC labels connections as either N (threads iNcluded) or X (threads eXcluded).

In double shear, the bolt is sheared across two plane at the same time. This happens in a clevis or where three plates is lapped together and the center plate pulls against the other two (opposite the outer pair). The capacity is just double the single shear value of each of those same planes.

In practical terms, sometimes there’s a mix of both: If one plane runs through the shank and another through the threads, then you’d add the two single-plane values instead of doubling either.

Order your bolts long enough that the smooth shank covers all of the shear planes. Partially threaded bolts with the proper grip length center better in the hole and are stronger in shear. They do not damage the plate bores from the threads.

DIN 933 fully threaded bolts will always have threads in the plane, and thus always use the lower column values.

These are ultimate values with no safety factor, which also neglects plate-side failure modes. Typicaly in soft or thin plates, the bolt does not shear before there is bearing, tear-out or block shear in the plate itself. This means that checking just the bolt isn’t a thorough check of the joint.

The numbers are design resistances to be compared against factored loads.

Each number is calculated as Fv,Rd = alpha v x fub x A / gamma M2. The recommended partial factor, gamma M2 ,is 1.25, applied to bolts per shear plane and bolt. Select the column corresponding to which bolt type and if it is smooth shank or threaded section that lies in the shear plane.

What this means is that instead of using the old 0.6 rule, we use what’s called the alpha v coefficient (which does have one caveat you’ll want to remember). For bolts with their threads in the shear plane, the coefficient alpha v is 0.6 for classes 4.6, 5.6, 8.8 and 0.5 for classes 4.8, 5.8, 6.8 and 10.9.

Why is that? A 0.6 coefficient applies well enough for lower strength, softer thread material. However, when the threads is in the shear plane, those higher strength, harder, cold worked threads aren’t as ductile in shear, so they gets a lower coefficient.

Therefore, if you look at two identical bolts, say an M20 class 10.9 bolt versus an M20 class 8.8 bolt, the first is rated for a design shear resistance of 98.0 kN, which is only slightly more than the 94.1 kN of the second. Class 10.9 bolts provides increased shear capacity on the shank itself. This is because the alpha v coefficient rise back up to 0.6 across all classes.

The nominal ultimate strengths (fub) are 1000 and 800 MPa. This is why I don’t want you to compare this chart with the earlier ultimate-load table: That table use the minimum ultimate strength values (ISO 898-1). Those are 830 and 1040 MPa.

Shank columns represent the gross area, and threads columns represents the tensile stress area. I list both out in case you need to track something down to the original.

The above resistances apply only to the bolt shear check. A complete EN 1993-1-8 connection check includes block tearing checks. It also includes adhering to spacing and edge distance rules and checking the bearing resistance of the connected plates. In the case of thin plates, bearing resistance is frequentely governing.

If it is a category B or C slip-critical connection, then instead (or in addition) of bolt shear, check slip resistance of preloaded 8.8 or 10.9 assemblies per EN 14399.

In practice, the typical preloaded structural assemblies will be between M12 and M36, including smaller sizes as the EN 1993-1-8 allows ordinary bearing-type bolts from M5 upwards in light steelwork.

The value for the gamma M2 factor can vary according to National Annexes. Therefore, check the applicable factor for your country before completing the design.

This is the nominal single shear strength (in kips) for classic US structural bolts.

This is AISC 360 Table J3.2, as listed here. Pick your bolt spec and condition based off diameter, then it’s Rn in kips per shear plane. For LRFD, use a resistance factor (phi) of 0.75. For ASD, divide by 2.00 for your safety factor (omega). Use a double shear connection, multiply by 2 planes.

AISC handles the thread question differently than the derived charts: it always use the full nominal bolt area Ab and bakes the thread penalty into the stress.

The nominal shear stresses Fnv are: 27 ksi for A307. The nominal shear stresses Fnv for A325 and Group A is 54 ksi (N) or 68 ksi (X). 68 ksi (N) or 84 ksi (X) for A490 and Group B.

The N suffix indicate that threads are included in the shear plane. The X suffix indicates that they are not. If you are not sure of your grip length, you'd specify N. This will impose a roughly 20 percent penalty on strength but you accept it by choosing N.

The Fnv stresses comes from 0.563 x UTS for X and 0.45 x UTS for N. Remember that 0.6 is the shear ratio we use all the time.

Here that 0.6 is multiplied by an 0.80 reduction for non-uniform shear, sized for end-loaded connections up to 38 inches long. In this case, the gross area is used in the formula. So an AISC nominal value will never equal 0.6 x UTS x As from the earlier tables. The two chart family cannot be mixed together in the same calculation.

A325 bolts are produced in the 1/2 to 1 1/2 inch range. Above 1 inch, the old A449 spec filled in. Grades A325 and A490 is unified today as grades within ASTM F3125.

Never use a galvanized A490 bolt. Do not reuse an A325 or A490 bolt after fully pre-tensioning it. A307 bolts has no X/N designation. The code assumes these bolts have threads in the plane.

Just like Eurocode, there is a limit state of bolt shear. There are checks on block shear. There are checks on tear-out at the bolt hole. There are checks on bearing at the bolt hole. There are slip resistance checks for slip-critical joints.

For slip-critical joints you have a set of slip coefficients. The bearing strength is often that of the connected plate if it's thin material. These strengths can be use directly for snug-tight bearing joints. They represent an upper bound for slip critical joints.