For hex bit sockets, ISO 1174 is the governing document for the dimensions listed below. Mechanical and performance requirements for this part family are set by its own standards, not by the bolt and screw property-class documents.
ISO 1174 — Scope
The table below lists the dimensions catalogued for hex bit sockets under ISO 1174. The scope of ISO 1174 itself is not summarised here — where a figure matters, confirm it against the published document.
Tolerance & Product Grades
Product grade is a concept from dimensional fastener standards and does not apply to ISO 1174. Tolerances for this part are the limits shown against each dimension in the table.
Dimensions Specified by ISO 1174
| Hex size | Square drive | Mating socket screw | Purpose |
|---|---|---|---|
| 3 mm | 1/4 in | M4 | torque-controlled tightening |
| 4 mm | 1/4 in | M5 | torque-controlled tightening |
| 5 mm | 3/8 in | M6 | torque-controlled tightening |
| 6 mm | 3/8 in | M8 | torque-controlled tightening |
| 8 mm | 1/2 in | M10 | torque-controlled tightening |
| 10 mm | 1/2 in | M12 | torque-controlled tightening |
| 14 mm | 1/2 in | M16 | torque-controlled tightening |
Equivalent Standards
Where direct equivalents exist (ISO ↔ DIN, ISO ↔ ASME), they are listed on the parent Hex Bit Sockets page.
Always confirm against the dimensions on this page, since some "equivalent" standards differ in tolerances and head geometry.
When to Specify ISO 1174
Choose ISO 1174 for international engineering work and OEM supply where ISO standards are the contractual reference. It is the default modern specification for hex bit sockets.
Custom manufacturing · Made to drawing
Need a fastener tool to this standard in a non-standard size?
Parts built to ISO 1174 are already in the catalog, so a special is usually a variation on existing tooling rather than a new design — which is what keeps the cost down.
Minimum order from 2,000 pieces; samples within 7 days of drawing approval.
