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Hex Castle Nut Dimensions (DIN 935, M4 to M16)

Guide · Updated October 28, 2026

DIN 935 covers hex slotted and castle nuts. Pitch P, wrench size s, e min, height m, slot width n, w max and the DIN 94 split pin agree across the fasteners.eu DIN 935 table and the Torqbolt DIN 935 table, with M12 to M16 also matching the Intafast DIN 935-1 data sheet and M4 to M8 and M16 matching the Aspen Fasteners DIN 935 sheet. Not shown: M7 and fine-pitch rows, M18 and up, and the older 17 / 19 mm wrench rows Aspen lists for M10 / M12. Check the current edition or your supplier for critical work.

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Step by step

  1. Confirm the size: DIN 935 covers hex slotted nuts (M4 to M10) and castle nuts with a turned crown (M12 and up). This chart shows M4 to M16 coarse pitch.
  2. Pick the wrench: s is the wrench size: M6 10 mm, M8 13 mm, M10 16 mm, M12 18 mm, M16 24 mm. Older stock may be M10 17 mm and M12 19 mm.
  3. Check the height: m is the total nut height including the slots: M8 9.5 mm, M12 15 mm.
  4. Check the slot: n is the slot width: M8 2.5 to 2.75 mm. w max is the height from the bearing face to the slot bottom: M8 6.5 mm.
  5. Pick the split pin: Use the DIN 94 split pin listed: M8 2 x 16, M12 3.2 x 22, M16 4 x 28.
  6. Drill the bolt: Torque to spec, then back off or go on to the next slot, never past torque, and drill the cross hole so it lines up inside the slot.

DIN 935 castle nut dimensions (mm)

Columns: thread size, coarse pitch P, wrench size s, width across corners e min, nut height m, slot width n min–max, slot bottom height w max, DIN 94 split pin. Sizes in brackets are non-preferred.

Worked example: M12 castle nut on a clevis

An M12 DIN 935 nut takes an 18 mm wrench, stands 15 mm tall, and its slot bottoms are at most 10 mm above the bearing face. The cross hole in the bolt should sit about 10 to 13 mm above the washer face so the 3.2 x 22 split pin passes through a slot. Tighten to torque, then go to the next slot that lines up and fit the pin.

Slotted vs castle form

M4 to M10 DIN 935 nuts are slotted hex nuts: the slots cut down into the hex. From M12 up the top is turned to a round crown (de 15.57 to 16 mm on M12, 21.48 to 22 mm on M16) and the slots are in the crown. Both take the same DIN 94 split pin sizes.

Common problems

FAQ

What is a DIN 935 nut?

A hex nut with radial slots on top for a split pin (cotter pin). Up to M10 the slots are cut into the hex; from M12 up they are in a smaller round crown, called a castle nut.

What split pin fits a DIN 935 nut?

The DIN 94 pin sizes are: M6 1.6 x 14, M8 2 x 16, M10 2.5 x 20, M12 3.2 x 22, M16 4 x 28.

What wrench fits a DIN 935 M12 castle nut?

18 mm in the current edition. Older parts made to the DIN 934 wrench sizes are 19 mm, and M10 can be 17 mm instead of 16 mm.

Should I loosen a castle nut to line up the pin?

No for torque-critical joints. Tighten to the low end of the torque spec and keep going to the next slot. On wheel bearings, follow the maker procedure.

How is DIN 935 different from DIN 937?

DIN 937 is the thin (low) castle nut. DIN 935 is the regular height version.

Is M14 a standard size?

M14 is non-preferred (in brackets). M4 to M12 and M16 are easier to buy.

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General shop information only — follow your drawing, tool maker's data and your quality system.