Bolt and Screw Terminology

Here are some specific DIN references for standard metric bolts with partial threads—whether hex head or Allen (socket) head.

The common ones are:

Hex Head Bolts

DIN 931 (coarse thread)
- Hexagon head bolts, partially threaded
- Replaced by ISO 4014 / EN ISO 4014 in newer standards.
DIN 933 (coarse thread)
- Hexagon head screws, fully threaded
- Replaced by ISO 4017 / EN ISO 4017.
Tip: If you see a hex head fastener with only a portion of the shank unthreaded, it usually corresponds to DIN 931 (older DIN) or ISO 4014 (newer standard).

DIN 912
- Hexagon socket head cap screws.
- Depending on the length (relative to diameter), they can be either fully or partially threaded. In practice, many DIN 912 screws under a certain length end up fully threaded, while longer sizes often have an unthreaded portion.
- The current ISO equivalent is ISO 4762.

Partially threaded vs. fully threaded:
- The unthreaded portion on partially threaded fasteners is sometimes called the “grip length” or “plain shank.”
Bolt vs. Screw:
- In everyday use, people often say “bolt” for anything with a head and threads. Technically, a “bolt” is intended for use with a nut, while a “screw” is intended to go into a tapped hole. In ISO/DIN standards, “hex head screw” and “hex head bolt” often appear somewhat interchangeably.
Older DIN vs. New ISO:
- Many of the classic DIN standards (e.g., DIN 931, DIN 933, DIN 912) have been superseded by ISO standards (e.g., ISO 4014, ISO 4017, ISO 4762). The dimensions are similar but not always 100% identical, so check if you need the exact older DIN spec or the newer ISO/EN spec.

Head Type	Partial Thread	Full Thread	Current ISO / EN Standard
Hex Head (coarse pitch)	DIN 931 (ISO 4014)	DIN 933 (ISO 4017)	ISO 4014 / ISO 4017
Hex Socket / Allen	DIN 912 (length-based)	DIN 912 (length-based)	ISO 4762

Bottom Line:

For partially threaded hex head bolts, refer to DIN 931 or its ISO equivalent ISO 4014.
For Allen (socket) head bolts with partial threads, it’s under DIN 912 (or ISO 4762). Whether they are partially or fully threaded in a given length typically depends on the fastener’s nominal length and diameter.