Metric Size
M20
M20 coarse thread — 2.5 mm pitch, 17.5 mm tap drill, 22 mm normal clearance hole, 17 mm hex key.
Last verified: 2026-07-10
| Pitch(mm)Coarse-thread pitch (ISO 261). | 2.5 |
|---|---|
| Tap drill(mm)For ~75% thread — major Ø minus pitch. | 17.5 |
| Clearance (normal)(mm)Normal clearance hole (ISO 273). | 22 |
| Hex key(mm)Socket cap-screw hex key (ISO 4762). | 17 |
| Typical use | Heavy structural / high-load bolting |
Other metric fastener reference
Sources
- ISO 261 — ISO general-purpose metric screw threads (coarse pitch)
- ISO 273 — clearance holes for bolts and screws (normal fit)
- ISO 4762 — hexagon socket head cap screws (hex key sizes)