M5 A2 Stainless Steel Socket Cap Screws (Allen Bolts) DIN 912 / ISO 4762
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- Standard DIN 912 / ISO 4762
- Grade A2 (304)
- Drive Hex socket
How to measure DIN 912 / ISO 4762 socket cap screws
Thread size to diameter
- M1.61.6mm
- M22mm
- M2.52.5mm
- M33mm
- M44mm
- M55mm
- M66mm
- M88mm
- M1010mm
- M1212mm
| Dimension | Symbol | Value |
|---|---|---|
| Thread size and pitch | d / P | M5 x 0.8 mm |
| Head diameter (max) | dk | 8.50 mm |
| Head height (max) | k | 5.00 mm |
| Hex socket size | s | 4 mm |
| Socket depth (min) | t | 2.5 mm |
| Thread length, partially threaded lengths (ref.) | b | 22 mm |
| Length, under the head (head not included) | L | 6 to 100 mm (23 lengths) |
| Property class and tensile strength (min) | Rm | A2-70, 700 N/mm² |
M5 socket cap screws in A2 stainless steel, also sold as M5 allen bolts and M5 cap head bolts. The cylindrical head has a hex socket in the top, so a 4mm hex key tightens them from straight above and the head can sit down in a counterbore. Dimensions follow DIN 912 / ISO 4762.
The M in M5 is the thread diameter in millimetres, and it is not the hex key size. An M5 screw has a 5mm thread but takes a 4mm key, so check the socket size in the table before you buy a key. The full M5 cap head bolt dimensions are also in the downloadable PDF spec sheet.
There are 23 lengths, from 6mm to 100mm. We have no minimum order, whether you need ten screws or a full box, and the price per screw falls as the quantity goes up.
Where M5 socket cap screws are used
The head is only as tall as the thread is wide, so an M5 head stands 5mm proud. That makes socket cap screws a good fit for machinery, tight spaces and jobs where a hex head and spanner will not fit. They are commonly used on motorbikes, kit cars and model making, and across general engineering.
Choosing the length of an M5
Length is measured under the head, so an M5 x 20 reaches 20mm into the part and the head sits on top. The range runs from 6mm to 100mm in 23 lengths. Up to 25mm the thread runs the full length of the screw.
From 30mm the screws are partially threaded, with a plain shank under the head and at least about 22mm of thread at the tip. That figure is the standard's reference length of 2 x the diameter plus 12mm, and it is the same at every length. On a partially threaded screw the plain shank is the part that lines up with the top plate, and the thread does the gripping in the bottom one.
Property class 70 starts at M5 in our range, and M6 and every larger size share it. M4 and the smaller sizes are class 50.
A2 stainless steel, class 70
A2 is 304 stainless steel, also written 18/8. It resists rust in damp and in ordinary outdoor use, which is why it is the usual choice for general work. M5 in A2 is property class 70, a minimum tensile strength of 700 N/mm².
Near salt water, pools or chemicals, A4 stainless lasts longer because it contains molybdenum. The same screw is available in A4 stainless and, for higher strength, in 12.9 high tensile steel. Class 12.9 has a minimum tensile strength of 1220 N/mm², but it offers little protection against rust.
Our A2 stainless steel and A4 stainless steel guides cover each grade in detail, and A2 vs A4 stainless steel compares them side by side. For lifting or other safety-critical joints, check the strength your design needs before choosing a screw.
Questions about M5 socket cap screws
What size Allen key fits an M5 socket cap screw?
A 4mm hex key. The M number is the thread diameter and is not the same thing as the key size, so M5 takes a 4mm key, M6 takes 5mm, M8 takes 6mm and M10 takes 8mm.
Is DIN 912 the same as ISO 4762?
ISO 4762 replaced DIN 912, and both names are still in everyday use. Suppliers and manufacturers tend to say DIN 912, while engineers often specify ISO 4762.
For an M5, the thread, head, socket and thread length figures in the table are the same in both. The standards differ in some tolerances and secondary dimensions that the table does not show. Our DIN 912 guide goes through the standard in more detail.
How long is the thread on an M5 socket cap screw?
Screws up to 25mm are threaded along the whole length. From 30mm, the thread is at least about 22mm long at the tip, and the rest is plain shank. The 22mm is a reference figure (2 x the diameter plus 12mm) and does not change with length.
How do I measure the length of a socket cap screw?
Measure from the underside of the head to the tip, with the head left out. An M5 x 20 is 20mm under the head, and about 25mm overall once you add the 5mm head.