← AskMachinist · Guides · Calculator · 🔎 Search

Round Nut with Pin Holes Dimensions (DIN 1816, M6 to M22)

Guide · Updated October 28, 2026

DIN 1816 covers round nuts with set pin holes in the side, in ISO metric fine thread. The outside diameter d2, face diameter d3, height h, pin hole diameter d4, hole depth t and hole count below agree across the fasten.it DIN 1816 table, the fasteners.eu DIN 1816 table and the DigiPich DIN 1816 sheet (M20x1.5 agrees in two; the third has a damaged row). Skipped: M24x1.5 and up, because the sources list sizes against different rows there. Tolerances: d2 h11, h h14, d4 H11; raised face height z is 0.5 mm. Check the current edition or your supplier for critical work.

Need an exact reference size?

Build any gage block stack with the free Gage Block Calculator. Free, no login.

Step by step

Measure the thread: Measure the shaft or spindle thread major diameter and pitch; DIN 1816 uses ISO metric fine thread (M12x1.5, M16x1.5 and so on).
Pick the nut row: Find the thread in the chart to get the outside diameter d2 and height h.
Check the space: Make sure d2 and h clear the housing, bearing or pulley face the nut sits against.
Size the pin spanner: Pick a pin (face or side) spanner whose pin fits hole diameter d4 and reaches the nut diameter.
Tighten through a hole: Put the spanner pin in one of the four side holes and tighten; move to the next hole as you go.
Lock it: Lock with a set screw, a tab washer, a second nut or thread locker, since a plain round nut can back off.

DIN 1816 round nut dimensions (mm)

Columns: thread d, outside diameter d2, face diameter d3, height h, pin hole diameter d4, hole depth t, number of holes.

Thread d | d2 | d3 | h | d4 | t | Holes
M6x0.75 | 16 | 12 | 5 | 2.5 | 4 | 4
M8x1 | 20 | 16 | 5 | 2.5 | 4.5 | 4
M10x1 | 25 | 20 | 6 | 3 | 4.5 | 4
M12x1.5 | 28 | 23 | 6 | 3 | 5 | 4
M14x1.5 | 30 | 25 | 7 | 4 | 5 | 4
M16x1.5 | 32 | 27 | 7 | 4 | 6 | 4
M18x1.5 | 34 | 28 | 8 | 4 | 6 | 4
M20x1.5 | 36 | 30 | 8 | 4 | 6 | 4
M22x1.5 | 40 | 34 | 9 | 4 | 6 | 4

Worked example: M16x1.5 spindle

A M16x1.5 shaft end takes a DIN 1816 M16x1.5 nut: 32 mm across, 7 mm tall, with four 4 mm holes 6 mm deep. Leave at least 33 mm of clear diameter and 7 mm of thread past the part, and use a pin spanner with a 4 mm pin.

Pin holes vs slots vs hex

Pin holes (DIN 1816): smooth outside, low height, needs a pin spanner.
Slots (DIN 1804, DIN 981): hook spanner, common on bearings.
Hex: standard wrench, but needs more radial room.

Common problems

Pin too small for the hole: it cams out and burrs the edge; match d4.
Nut loosening: add a locking method.
Coarse thread bought by mistake: DIN 1816 is fine thread only.

FAQ

What is a DIN 1816 nut?

A round steel nut with blind pin holes drilled radially into its outside diameter. It is turned with a pin spanner instead of a wrench, so it fits where a hex will not.

Why does the M6 to M22 range use four holes?

In our sources all sizes up to M42 have four side holes; six and eight holes start on the larger sizes.

How is DIN 1816 different from DIN 1804 or DIN 981?

DIN 1804 nuts have slots on the outside for a hook spanner; DIN 981 (KM) bearing lock nuts also use slots. DIN 1816 uses round pin holes in the side instead.

What do d3 and z mean?

d3 is the diameter of the small raised bearing face on one side, and z is its height (0.5 mm on these sizes).

Why stop at M22?

Our three sources do not line up past M22: one shifts every size by a row. We only show rows where they agree. The standard runs up to M200x3.

What grade are DIN 1816 nuts?

Our sources list steel class 6 with 4H thread tolerance.

Related guides and calculators

Build your stack in seconds

The free Gage Block Calculator finds the fewest-block combination for inch and metric sets, with wear blocks. No login.

Questions? Ask a machinist.

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