# 6923 — Fastener standard equivalences: DIN to ISO / EN crossover

For 6923, fastener description is Hexagon nuts with flange; iso equivalent is 4161; en iso number is 1661; interchangeability is Fine thread omitted to be included in a separate standard later); width across flat M10 changed; modification notes is Fine thread omitted to be included in a separate standard later); width across flat M10 changed, verified against its source on 2026-08-12.

- **DIN standard:** 6923 _(verified: appears in the quote below)_
- **Fastener description:** Hexagon nuts with flange _(verified: appears in the quote below)_
- **ISO equivalent:** 4161 _(verified: appears in the quote below)_
- **EN ISO number:** 1661 _(verified: appears in the quote below)_
- **Interchangeability:** Fine thread omitted to be included in a separate standard later); width across flat M10 changed _(verified: appears in the quote below)_
- **Modification notes:** Fine thread omitted to be included in a separate standard later); width across flat M10 changed _(verified: appears in the quote below)_

## What the source says

> Hexagon nuts with flange | 6923 | | 1661 | | 4161 | 1998-02 | Hexagon nuts with flange | Fine thread omitted to be included in a separate standard later); width across flat M10 changed |

## Sources disagree

More than one authority states this, and they do not state the same
thing. Both are reproduced with the source each came from.

### Fastener description

fullerfasteners.com says fastener description is **Hexagon nuts with flange**, as of 2026-08-12.

> Hexagon nuts with flange | 6923 | | 1661 | | 4161 | 1998-02 | Hexagon nuts with flange | Fine thread omitted to be included in a separate standard later); width across flat M10 changed |

Source: https://fullerfasteners.com/tech/din-iso-en-crossover-chart/

monsterbolts.com says fastener description is **Flange geometry/tolerance.**, as of 2026-08-12.

> DIN 6923 | DIN EN 1661 | Check spec

Source: https://monsterbolts.com/pages/common-din-numbers-for-metric-fasteners

trfastenings.com says fastener description is **Hexagon Nuts with flange**, as of 2026-08-12.

> DIN 6923 | ISO 1661 | | Hexagon Nuts with flange |

Source: https://www.trfastenings.com/knowledge-base/engineering-data/fastener-standards


### ISO equivalent

fullerfasteners.com says iso equivalent is **4161**, as of 2026-08-12.

> Hexagon nuts with flange | 6923 | | 1661 | | 4161 | 1998-02 | Hexagon nuts with flange | Fine thread omitted to be included in a separate standard later); width across flat M10 changed |

Source: https://fullerfasteners.com/tech/din-iso-en-crossover-chart/

monsterbolts.com says iso equivalent is **1661**, as of 2026-08-12.

> DIN 6923 | DIN EN 1661 | Check spec

Source: https://monsterbolts.com/pages/common-din-numbers-for-metric-fasteners

trfastenings.com says iso equivalent is **1661**, as of 2026-08-12.

> DIN 6923 | ISO 1661 | | Hexagon Nuts with flange |

Source: https://www.trfastenings.com/knowledge-base/engineering-data/fastener-standards


### Interchangeability

fullerfasteners.com says interchangeability is **Fine thread omitted to be included in a separate standard later); width across flat M10 changed**, as of 2026-08-12.

> Hexagon nuts with flange | 6923 | | 1661 | | 4161 | 1998-02 | Hexagon nuts with flange | Fine thread omitted to be included in a separate standard later); width across flat M10 changed |

Source: https://fullerfasteners.com/tech/din-iso-en-crossover-chart/

monsterbolts.com says interchangeability is **Check spec**, as of 2026-08-12.

> DIN 6923 | DIN EN 1661 | Check spec

Source: https://monsterbolts.com/pages/common-din-numbers-for-metric-fasteners


## Source

- https://fullerfasteners.com/tech/din-iso-en-crossover-chart/
- https://monsterbolts.com/pages/common-din-numbers-for-metric-fasteners
- https://www.trfastenings.com/knowledge-base/engineering-data/fastener-standards

Last verified: 2026-08-12. Review by: 2028-08-11.
Part of [Fastener standard equivalences: DIN to ISO / EN crossover](https://referencesource.org/fastener-thread-standard-equivalence/).