ISO 7380 M8 × 25 Button head (low dome)
ISO 7380 M8 × 25 is a button head socket screw with a 25 mm nominal length, on a M8 × 1 mm metric thread. A low dome head with internal hex drive. Chosen when you want a finished look without machining a countersink.
Dimensions
- Standard
- ISO 7380
- Type
- Button head socket screw
- Size
- M8 × 25
- Thread
- M8 × 1
- Length L
- 25 mm
- Socket size s
- 5 mm
- Head diameter dk
- 14 mm
- Head height k
- 4.4 mm
- Drive
- Hexagon socket
- Head
- Button head (low dome)
Nominal values in millimetres as published in ISO 7380. Estimated weight 15.182 g per piece in steel (15.278 g in stainless), calculated from the nominal geometry — real parts vary with tolerance and head chamfers.
Thread data
Full M8 thread pageOther lengthsISO 7380 M8
All M8 specificationsChoosing and fitting this size
ISO 7380 M8 × 25 is a button head (low dome) in M8, 25 mm long under the head, on a 1 mm coarse pitch. Mating threads should be a matching class nut or a tapped hole of the same nominal size.
Common stock grades are 8.8, 10.9 and 12.9 in steel, plus A2-70 and A4-80 in stainless. Class 10.9 and 12.9 carry roughly 1.25 and 1.5 times the proof load of 8.8, but they also need a properly rated mating nut — a class 8 nut under a 12.9 bolt simply moves the failure into the thread. Zinc-plated 10.9 and above should be baked to avoid hydrogen embrittlement.
For a tapped hole, M8 × 1 mm takes a 7 mm tap drill, and the external thread's minor diameter is 6.77 mm — that is the section carrying the load, not the nominal M8 figure. Thread engagement of at least one times the nominal diameter is what lets the bolt fail before the thread strips.