M8 screw and bolt sizes for the more common ones we deal with. This will give information about the maximum screw head heights and head diameters as well as the driver size needed to install or remove them. If unfamiliar with DIN and ISO numbers, they can be thought of as exact fastener names for each specific screw and are usually given as either DIN or ISO (eg. DIN 912 or ISO 7380).
Metric M8-1.25, Coarse Thread
All of these will take a matching M8 Nut and Washer
Note: PT / FT = Partial Thread / Full Thread
* 'Width Across Flats' measurement given
FAQs
M8 is the designation for a metric (M) sized bolt or screw that is 8mm (8) in diameter. This is roughly equivalent to a 5/16 bolt or screw.
What size is a standard M8 screw? ›
M8 is the designation for a metric (M) sized bolt or screw that is 8mm (8) in diameter. This is roughly equivalent to a 5/16 bolt or screw.
What is the difference between M8 bolt and M8 screw? ›
An M8 Bolt or screw refers to the bolts diameter in Millimeters. It is a metric measurement. M8 can be either a nut or a bolt. A standard 8 millimeter diameter bolt will have a thread pitch of 1.25 millimeters per revolution and be designated: M8-1.25.
What does M8 1.25 mean on a bolt? ›
The first number, 8, represents the bolt's nominal diameter in millimeters, while the second number, 1.25, represents the distance between each thread crest. This means that for every 1.25 millimeters of axial distance along the bolt, one complete turn of the thread occurs. The size and p.
Are 5 16 and M8 the same? ›
A 5/16 Hanger Bolt and M8 (or 8mm) hanger bolt are very similar in size, but have different threading on them. Because of this different threading, a 5/16 hanger bolt is not compatible with an M8 bolt.
What size hole for an M8 bolt? ›
When using the M8 Bolt, you will need to drill a 8mm diameter hole into the substrate and there will need to be a 10mm diameter clearance hole in the item to be fixed in position.
What size hole for M8 screws? ›
Metric threads
| Thread | Drill size for tapping standard metric threads | Clearance hole |
|---|
| M8 | 6.8 | 9 |
| M10 | 8.5 | 11 |
| M12 | 10.2 | 13.5 |
| M14 | 12 | 15.5 |
20 more rowsFor the threaded rod 8mm vs 5/16" makes literally no difference. For the smooth rods 5/16" will work, but will not work with LM8UU linear bearings. You would have to have bearings or bushings made specifically for 5/16" rod.
What is equivalent to M8 bolt? ›
Thread conversion table
| Metric coarse | Metric fine | UNC |
|---|
| M6 x 1 | M6 x 0.75 | 1/4-20 |
| M8 x 1.25 | M8 x 1 | 5/16-18 |
| M10 x 1.5 | M10 x 1.25 | 3/8-16 |
| M12 x 1.75 | M12 x 1.25 | 1/2-13 |
12 more rows| Fastener Sizes in Inches |
|---|
| Metric & Inch Size | Diameter (inches) | Rounded to Nearest 64th (inches) |
|---|
| 5/16 | 0.3125 | 5/16 |
| M8 | 0.3150 | 5/16 |
| 3/8 | 0.3750 | 3/8 |
42 more rows| Size | Grade 8.8 | Grade 10.9 |
|---|
| M8 | 2,120kg | 3,040kg |
| M10 | 3,370kg | 4,810kg |
| M12 | 4,890kg | 7,000kg |
| M16 | 9,100kg | 13,000kg |
5 more rowsM8 bolts are highly adaptable strong fixings which can be used in many applications, such as securing heavy timbers, metals or concrete. With a full or half threaded stem they can be used with either a nut or into a tapered hole.
How do I know what size bolt I need? ›
To determine bolt diameter, measure the distance from the outer thread on one side to the outer thread on the other side. This is called major diameter. Alternatively, you can measure the bolt shank diameter. The shank is known as the body or sometimes, the shoulder.
What is the difference between M8 1.25 and M8 1? ›
For metric fasteners, you will see a M8 x 1.25 or an M8 x 1. For thread pitch, the distance between two points is the second number meaning the higher the number the fewer threads there are. This means the M8 x 1.25 is the coarse threading and the M8 x 1 is the fine thread.
What size is M8 in inches? ›
| Tap size | Basic major dia (mm) | Basic major dia (inch) |
|---|
| M8 x 1 | 8mm | .3150 |
| M10 x 1.5 | 10mm | .3937 |
| M10 x 1.25 | 10mm | .3937 |
| M12 x 1.75 | 12mm | .4724 |
24 more rowsHere's an example metric bolt specification: M8-1.0 x 20. This bolt specification breaks down like this: The letter 'M' indicates that this bolt uses a metric thread. The number '8' refers to the nominal diameter of the bolt shaft in millimeters.
Is #8 the same as M8? ›
The 8 is the nominal diameter in millimeters. 1″ = 25.4 mm, so it is similar diameterr to 5/16–18 UNC, but the threads don't match at all. The M8 has a standard thread pitch of 1.25 mm.
Are M8 bolts 8 mm? ›
The defined diameter of metric bolts is actually slightly larger than the actual diameter of the bolt shaft. So an M8 bolt would have a shaft diameter that's slightly under 8mm which means that the bolt should fit through an 8mm hole.
What size is a M8 8 screw? ›
The M8 machine screw has a thread diameter of 8 millimetres, in simple terms the M stands for millimetres followed by the size – in this case 8mm.
Metric M8-1.25, Coarse Thread