# DIN 558 — DIN / ISO / BS fastener equivalents and the sizes where they are not interchangeable

For DIN 558, iso standard is ISO 4018; part is Hex Head Bolts (FT), Metric Coarse; interchangeability verdict is Fully interchangeable, verified against its source on 2026-08-05.

- **DIN standard:** DIN 558 _(verified: appears in the quote below)_
- **ISO standard:** ISO 4018 _(verified: appears in the quote below)_
- **Part:** Hex Head Bolts (FT), Metric Coarse _(verified: appears in the quote below)_
- **Interchangeability verdict:** Fully interchangeable _(verified: appears in the quote below)_

## What the source says

> Hex Head Bolts (FT), Metric Coarse | DIN 558 | ISO 4018 | Fully interchangeable | Alt coarse hex FT.

## 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.

### Part

monsterbolts.com says part is **Hex Head Bolts (FT), Metric Coarse**, as of 2026-08-05.

> Hex Head Bolts (FT), Metric Coarse | DIN 558 | ISO 4018 | Fully interchangeable | Alt coarse hex FT.

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

trfastenings.com says part is **Hexagon Head Screws**, as of 2026-08-05.

> DIN 558 | ISO 4018 | | Hexagon Head Screws |

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


## Source

- https://monsterbolts.com/pages/common-din-numbers-for-metric-fasteners
- https://www.trfastenings.com/knowledge-base/engineering-data/fastener-standards

Last verified: 2026-08-05. Review by: 2029-08-04.
Part of [DIN / ISO / BS fastener equivalents and the sizes where they are not interchangeable](https://referencesource.org/fastener-standard-interchangeability-exceptions/).