M8 is one of the standard coarse-thread sizes for hex nut under GB/T 41 / ISO 4034. 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 (GB/T 41 / ISO 4034)
| Size | Pitch (mm) | Width across flats s (mm) | Width across corners e (mm) | Nut height m (mm) | Reference standard |
|---|---|---|---|---|---|
| M8 | 1.25 | 13.0 | 14.38 | 6.8 | ISO 4032 / GB/T 6170 |
Spanner & Drive for M8 Hex Nut — GB/T 41 / ISO 4034 (Series 060)
M8 Hex Nut — GB/T 41 / ISO 4034 (Series 060) 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 Nut — GB/T 41 / ISO 4034 (Series 060)
M8 Hex Nut — GB/T 41 / ISO 4034 (Series 060) are commonly specified for general-purpose joints in machinery, fixturing and equipment frames.
Installation Tips for M8 Hex Nut — GB/T 41 / ISO 4034 (Series 060)
- 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.