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Low Head Socket Cap Screw Dimensions (DIN 7984, M3 to M24)

Q: How is DIN 7984 different from ISO 4762 / DIN 912?

Same head diameter, but a lower head (M8: k 5 vs 8 mm) and a hex socket one size smaller.

Q: How is DIN 7984 different from DIN 6912?

DIN 6912 keeps the ISO 4762 key size and adds a centring recess under the socket. DIN 7984 has a smaller key, no recess, and a slightly lower head from M10 up.

Q: Can I torque it like ISO 4762?

No. The low head and small key take less torque; use the supplier rating.

Q: Why does b have a dash for M3 to M6?

The standard gives no b value for screws over 125 mm in these sizes.

Guide · Updated October 28, 2026

DIN 7984 covers low head hexagon socket cap screws, M3 to M24. Values agree across fasteners.eu and fasten.it (2022 edition), and Spinelli for M3 to M12. 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, M3 to M24.
Size the counterbore: Use dk and k. The head is the ISO 4762 diameter but much lower.
Get the right key: Column s: DIN 7984 takes a smaller key than ISO 4762, for example 5 mm instead of 6 mm on M8.
Check thread length: b is the minimum thread length; use the second b column for screws longer than 125 mm.

DIN 7984 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 t, thread length b for l ≤ 125 and for 125 < l ≤ 200.

Size | P | dk | k | s | e | t | b ≤125 | b ≤200
M3 | 0.5 | 5.5 | 2 | 2 | 2.3 | 1.5 | 12 | –
M4 | 0.7 | 7 | 2.8 | 2.5 | 2.87 | 2.3 | 14 | –
M5 | 0.8 | 8.5 | 3.5 | 3 | 3.44 | 2.7 | 16 | –
M6 | 1 | 10 | 4 | 4 | 4.58 | 3 | 18 | –
M8 | 1.25 | 13 | 5 | 5 | 5.72 | 3.8 | 22 | 28
M10 | 1.5 | 16 | 6 | 7 | 8.01 | 4.5 | 26 | 32
M12 | 1.75 | 18 | 7 | 8 | 9.15 | 5 | 30 | 36
(M14) | 2 | 21 | 8 | 10 | 11.43 | 5.3 | 34 | 40
M16 | 2 | 24 | 9 | 12 | 13.72 | 5.5 | 38 | 44
(M18) | 2.5 | 27 | 10 | 12 | 13.72 | 6.5 | 42 | 48
M20 | 2.5 | 30 | 11 | 14 | 16 | 7.5 | 46 | 52
(M22) | 2.5 | 33 | 12 | 14 | 16 | 8 | 50 | 56
M24 | 3 | 36 | 13 | 17 | 19.44 | 8 | 54 | 60

Worked example: M8 in a 10 mm plate

An M8 ISO 4762 head is 8 mm high and would leave only 2 mm under an 8 mm counterbore. A DIN 7984 M8 head is 13 mm across and 5 mm high, so a 14 mm by 5.5 mm counterbore leaves 4.5 mm of material. Use a 5 mm key, not 6 mm.

Common problems

Key spins loose: you grabbed the ISO 4762 key; DIN 7984 takes one size smaller (M10 = 7 mm).
Socket rounds out: torqued to the ISO 4762 value; the small, shallow socket cannot take it.
Head stands proud: the counterbore was cut too shallow or too tight; allow about 1 mm over dk and a little over k.

FAQ

How is DIN 7984 different from ISO 4762 / DIN 912?

Same head diameter, but a lower head (M8: k 5 vs 8 mm) and a hex socket one size smaller.

How is DIN 7984 different from DIN 6912?

DIN 6912 keeps the ISO 4762 key size and adds a centring recess under the socket. DIN 7984 has a smaller key, no recess, and a slightly lower head from M10 up.

Can I torque it like ISO 4762?

No. The low head and small key take less torque; use the supplier rating.

Why does b have a dash for M3 to M6?

The standard gives no b value for screws over 125 mm in these sizes.

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