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Low Head Socket Cap Screw Dimensions (DIN 6912, M4 to M36)
Guide · Updated October 28, 2026
DIN 6912 covers low head hexagon socket cap screws with a pilot recess, M4 to M36. Values agree across fasteners.eu, fasten.it (2021 edition) and the Spinelli datasheet. Nominal values; check the full standard for tolerances.
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Step by step
- Find the thread: Pick the row for your thread size, M4 to M36.
- Check the head: Read dk and k to size the counterbore. The head is about 30% lower than an ISO 4762 head.
- Pick the hex key: Column s is the key size. M8 takes a 6 mm key, the same as ISO 4762.
- Check engagement: Socket depth t1 is shallow, so seat the key fully before applying torque.
DIN 6912 low head socket cap screw dimensions (mm)
Columns: thread d, pitch P, head diameter dk max, head height k max, hex socket s, width across corners e min, socket depth t1, pilot recess diameter dh min, pilot recess depth t2 min, thread length b (l ≤ 125).
- Size | P | dk | k | s | e | t1 | dh | t2 | b
- M4 | 0.7 | 7 | 2.8 | 3 | 3.44 | 1.6 | 2 | 3.3 | 14
- M5 | 0.8 | 8.5 | 3.5 | 4 | 4.58 | 2 | 2.5 | 4 | 16
- M6 | 1 | 10 | 4 | 5 | 5.72 | 2.5 | 3 | 5 | 18
- M8 | 1.25 | 13 | 5 | 6 | 6.86 | 3 | 4 | 6.5 | 22
- M10 | 1.5 | 16 | 6.5 | 8 | 9.15 | 3.5 | 5 | 7.5 | 26
- M12 | 1.75 | 18 | 7.5 | 10 | 11.43 | 4 | 6 | 9 | 30
- (M14) | 2 | 21 | 8.5 | 12 | 13.72 | 4.5 | 7 | 10 | 34
- M16 | 2 | 24 | 10 | 14 | 16 | 5.5 | 8 | 11.5 | 38
- (M18) | 2.5 | 27 | 11 | 14 | 16 | 6 | 8 | 12.5 | 42
- M20 | 2.5 | 30 | 12 | 17 | 19.44 | 6.5 | 10 | 14 | 46
- (M22) | 2.5 | 33 | 13 | 17 | 19.44 | 7 | 10 | 15 | 50
- M24 | 3 | 36 | 14 | 19 | 21.73 | 7 | 12 | 16 | 54
- (M27) | 3 | 40 | 16 | 19 | 21.73 | 8.5 | 12 | 17 | 60
- M30 | 3.5 | 45 | 17.5 | 22 | 25.15 | 9 | 15 | 19 | 66
- (M33) | 3.5 | 50 | 19.5 | 24 | 27.43 | 10 | 16.5 | 20 | 72
- M36 | 4 | 54 | 21.5 | 27 | 30.85 | 11.5 | 18 | 24 | 78
Worked example: M10 counterbore
An M10 DIN 6912 head is 16 mm across and 6.5 mm high, against 10 mm for ISO 4762. A 17.5 mm by 7 mm counterbore sets it flush, which saves 3.5 mm of depth. Use an 8 mm hex key.
Common problems
- Rounded socket: the t1 socket is shallow, so the key was not seated fully or was worn; use a new key and seat it to the bottom.
- Head pulled off or cracked: torqued to the ISO 4762 value; low heads carry less load.
- Head stands proud: the counterbore is too small in diameter or has a corner radius, so the head sits on its edge; cut it at least 1 mm larger than dk.
FAQ
How is DIN 6912 different from ISO 4762 / DIN 912?
The head is lower (M10: k 6.5 vs 10 mm), and the socket has a pilot recess dh / t2 at the bottom. Head diameter and key size are the same.
What is the pilot recess?
A small centring hole below the hex socket, diameter dh and depth t2, used for centring or locating.
Can it take full ISO 4762 torque?
No. The low head reduces load capacity, so check the maker rating.
Why does one source list a different M4 k value?
One datasheet gives M4 k max as 2.88. Three other sources give 2.8, so the chart uses 2.8.
Which sizes are non-preferred?
Sizes in brackets: M14, M18, M22, M27, M33.
Related guides and calculators
- Torx socket head cap screws (ISO 14579)
- Low head socket screws (DIN 7984)
- Socket head cap screws (ISO 4762)
- Button head screws (ISO 7380)
- Countersunk socket screws (ISO 10642)
- All free machinist calculators
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