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Slotted Round Nut Dimensions (DIN 546, M2 to M16)
Guide · Updated October 28, 2026
DIN 546 covers slotted round nuts, from M2 to M16. Values agree across fasteners.eu, the Lederer catalogue, the Bossard BN 220 sheet (to M10) and PTS (to M16). Nominal dk, m and n and min t are shown. Check your supplier for critical work.
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Step by step
- Match the thread: Check the size and coarse pitch.
- Check the bore: The nut sits in a counterbore at least dk wide.
- Pick the driver: Use a DIN 3115 forked driver or a blade at least n wide.
- Tighten gently: The slots are shallow (t), so do not overload them.
- Lock it: Add threadlocker if needed.
DIN 546 slotted round nut dimensions (mm)
Columns: thread, pitch P, outside diameter dk, height m, slot width n, slot depth t min.
- Size | P | dk | m | n | t min
- M2 | 0.4 | 4.5 | 2 | 1 | 0.8
- M2.5 | 0.45 | 5.5 | 2.2 | 1.2 | 0.9
- M3 | 0.5 | 6 | 2.5 | 1.2 | 1
- (M3.5) | 0.6 | 7 | 3 | 1.4 | 1
- M4 | 0.7 | 8 | 3.5 | 1.4 | 1.2
- M5 | 0.8 | 9 | 4.2 | 2 | 1.5
- M6 | 1 | 11 | 5 | 2.5 | 2
- M8 | 1.25 | 14 | 6.5 | 3 | 2.5
- M10 | 1.5 | 18 | 8 | 3.5 | 3.2
- M12 | 1.75 | 21 | 10 | 4 | 3.8
- M16 | 2 | 26 | 12 | 4 | 3.8
Worked example: M6 slotted round nut
An M6 DIN 546 nut is 11 mm across and 5 mm tall, with a 2.5 mm slot at least 2 mm deep. Counterbore about 11.5 mm and 5 mm deep for a flush fit.
Common problems
- Slot breaks: the driver is too thin.
- Will not sit flush: the counterbore is too shallow.
- Loosens: add threadlocker.
FAQ
What is DIN 546?
The slotted round nut. It sits flush in a counterbore and is turned by a slot in its face.
Why do M2.5 values differ in some tables?
One table repeats the M2 row (4.5/2/1/0.8, pitch 0.4). Lederer, Bossard and PTS all give 5.5/2.2/1.2/0.9 at pitch 0.45, so the chart uses that majority.
What driver fits?
A DIN 3115 two-pin forked or slotted driver.
What was skipped?
The min/max tolerances and the M1 to M1.6, M14, M18 and M20 sizes, which only one table gives.
Two-hole alternative?
DIN 547.
Related guides and calculators
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- Knurled thumb nuts, thin (DIN 467)
- Wing nuts (DIN 315)
- Hex coupling nuts (DIN 6334)
- Hex nuts (ISO 4032)
- Round nuts with pin holes (DIN 1816)
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