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DIN 933

Hexagon head screw,threaded up to the head

Superseded by ISO 4017 (2022) · Still sold as DIN 933 · Sizes M1.6–M52
DIN 933 screw side view, threaded up to the head, showing three flats of the head with the width across corners e, the head height k, d and PDIN 933 screw side view, threaded up to the head, showing three flats of the head with the width across corners e, the head height k, d and P
Side view
DIN 933 screw seen from the head, with the width across flats (s) and the width across corners eDIN 933 screw seen from the head, with the width across flats (s) and the width across corners e
Head view
SizeP (mm, coarse)s (mm, nom.)e (mm, min)k (mm, nom.)dw (mm, min)Break (kN, min)Torque (N·m, µ 0.14)
M4
0.707.007.662.806.207.03.3
M5
0.808.008.793.507.2011.36.6
M6
1.0010.0011.054.008.8816.111.3
M8
1.2513.0014.385.3011.6329.327.3
M10
1.5016.0017.776.4014.6346.453.9
M12
1.7518.0020.037.5016.6367.493.1
M16
2.0024.0026.7510.0022.49125.3229.9
M20
2.5030.0033.5312.5028.19203.2464.0

Values per ISO 4017:2022. Breaking load per ISO 898-1; torque per VDI 2230, µ = 0.14.Differs from DIN 933

Work out the screw length you needOpens the bolted joint configurator with DIN 933 / ISO 4017 chosen.

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Calculators that use this standard: Tightening torque and screw loads

About DIN 933

What it is

A hex head screw threaded up to the head, turned with a spanner or socket. An M10 to DIN 933 takes a 17 mm spanner. The same screw with a plain shank under the head is DIN 931 / ISO 4014.

Where it is used

In machine frames, brackets and through bolts with a nut, where the head stays outside and a spanner can reach it. The site gives it in classes 8.8, 10.9 and A2-70.

DIN or ISO

ISO 4017 replaced DIN 933. The screws are interchangeable except in four sizes, whose width across flats (s) changed: M10 (17 to 16 mm), M12 (19 to 18), M14 (22 to 21) and M22 (32 to 34). DIN 933 stops at M52; M56 to M64 are ISO only.

Typical mistakes

  • Bringing a 17 mm spanner to an ISO 4017 M10. It needs 16 mm.
  • Mixing DIN and ISO screws of M10 to M14 or M22 in one joint: two widths across flats on the same job.
  • Choosing a through bolt too short. It must stick out at least two pitches past the nut (ISO 4753); the bolted joint configurator adds them.

References