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All Metal Lock Nut Dimensions (ISO 7042 / DIN 980, M5 to M36)

Guide · Updated October 28, 2026

ISO 7042 covers prevailing torque all metal hexagon high nuts, the metric stover style lock nut that replaced DIN 980. The top threads are distorted (crimped or ovalled) so the nut grips the bolt without a nylon ring, which lets it run hot. The table gives coarse pitch, width across flats s (wrench size), total height h max and min, wrenching height mw min, width across corners e min and bearing face dw min. Values agree between the ISO 7042:2012 table and the Nufast ISO 7042 production drawing, and s, e, h min and dw match ISO 4033 style 2 nuts in ASME B18.2.4.2M. Note on M12 and M24: ISO 7042:2012 lists h max 13.30 mm and 23.90 mm, but ISO 7042:2025 says 13.30 was a typing error and corrects M12 to 12.30 mm, and raises M24 to 24.00 mm. Because sources disagree, h max for those two sizes is left out of the table. The 2025 edition also adds M7, M18, M22, M27, M33 and M39, not listed here.

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Step by step

  1. Match the thread: Check diameter and pitch with a thread gage. This chart is coarse pitch M5 to M36.
  2. Pick the wrench: Across flats s matches ISO 4032 and ISO 7040: M6 10 mm, M8 13 mm, M10 16 mm, M12 18 mm. Older DIN 980 stock is often 17 mm at M10 and 19 mm at M12.
  3. Check the height: Total height h is close to the thread diameter (about 1 x D). Use h max for clearance under covers and in pockets.
  4. Use it where nylon fails: An all metal nut has no plastic ring, so it suits hot joints such as exhausts and engine parts where a nylon insert would soften.
  5. Leave thread past the nut: Run at least 2 full threads past the nut so the deformed locking zone is fully engaged.
  6. Limit reuse: The distorted top threads wear each time. If the nut spins on by hand, replace it.

ISO 7042 all metal lock nut dimensions (mm)

Columns: thread size, coarse pitch P, width across flats s max and min (s max is the wrench size), total height h max, h min, wrenching height mw min, width across corners e min, bearing face diameter dw min. Grade A through M16, grade B above. M14 is a second choice size.

All metal vs nylon insert height

Total height h max, ISO 7042 all metal vs ISO 7040 nylon insert: M6 6.00 vs 8.00 mm, M8 8.00 vs 9.50 mm, M10 10.00 vs 11.90 mm, M16 16.40 vs 19.10 mm, M20 20.30 vs 22.80 mm. The all metal nut is shorter because the locking feature is inside the steel body.

Worked example: bolt length for an M10 all metal nut

Clamping a 10 mm flange and a 12 mm bracket with one 2 mm ISO 7089 washer: grip 24 mm, nut h max 10.00 mm, plus 2 threads at 1.5 mm = 3 mm. Total 37 mm, so an M10 x 40 works.

Common problems

FAQ

Is DIN 980 the same as ISO 7042?

Close. ISO 7042 replaced DIN 980 for the all metal high nut, but older DIN 980 stock can use 17 mm at M10, 19 mm at M12 and 22 mm at M14, and heights differ slightly. Check the box.

What wrench fits an M8 all metal lock nut?

13 mm, same as a regular ISO 4032 or ISO 7040 nut.

What temperature can an all metal lock nut take?

Far more than a nylon insert nut, which is generally limited to about 120 C. The limit depends on steel, plating and property class, so check the supplier data.

How tall is an M10 ISO 7042 nut?

8.94 mm min to 10.00 mm max total height, with a minimum wrenching height mw of 6.43 mm.

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