M8 is one of the standard coarse-thread sizes for hex flange nuts under ISO 4161 / DIN 6923. The sections below reproduce the dimensional row, list the matching tools and hole sizes, and summarize where this size is normally specified.
M8 Dimensional Row (ISO 4161 / DIN 6923)
| Size | Pitch (mm) | Flange diameter dc (mm) | Nut height m (mm) | Width across flats s (mm) | Reference standard |
|---|---|---|---|---|---|
| M8 | 1.25 | 17.9 | 8.0 | 13.0 | ISO 4161 / DIN 6923 |
Spanner & Drive for M8 Hex Flange Nuts
M8 Hex Flange Nuts have a width across flats of 13.0 mm — fit a 13.0 mm open-ended spanner or socket. Use a 6-point socket for tight clearances and to reduce rounding; for repeated assembly choose a torque wrench so the joint preload is repeatable.
Common Applications for M8 Hex Flange Nuts
M8 Hex Flange Nuts are commonly specified for general-purpose joints in machinery, fixturing and equipment frames.
Installation Tips for M8 Hex Flange Nuts
- Use a 6-point socket where access allows — 12-point sockets are more prone to rounding the corners on smaller sizes.
- On flanged or serrated variants, do NOT add a separate flat washer — the flange already spreads the load and the washer can defeat the locking serrations.
Mating Parts for M8
Pair M8 with the matching M8 bolt or screw, plus a M8 flat washer where required to distribute load on softer materials.