# DIN 7991 · M3 · kmax. — Sizes where a DIN fastener and its ISO equivalent are not interchangeable

For DIN 7991, size is M3; dimension that differs is kmax; iso standard is ISO 10642; din value is 1.7; iso value is 1.86, verified against its source on 2026-10-12.

- **DIN standard:** DIN 7991 _(verified: appears in the quote below)_
- **ISO standard:** ISO 10642 _(verified: appears in the quote below)_
- **Size:** M3 _(verified: appears in the quote below)_
- **Dimension that differs:** kmax. _(verified: appears in the quote below)_
- **DIN value:** 1.7 _(verified: appears in the quote below)_
- **ISO value:** 1.86 _(verified: appears in the quote below)_

## What the source says

**ISO standard, DIN value and ISO value:** The source prints these values inside the passage below but does not name them there. The passage shows where each one appears; what ties them to this record is the position on the page, not anything the passage says.

> Thread M1.6 M2 M2.5 M3 M3.5 M4 M5 M6 M8 ISO 10642 – – – 6.72 – 8.96 11.2 13.44 17.92 dk max. DIN7991 – – – 6 – 8 10 12 13 ISO 10642 – – – 1.86 – 2.48 3.1 3.72 4.96 kmax. DIN 7991 – – – 1.7 – 2.3 2.8 3.3 4.4

## Source

- https://www.wurthindustry.ca/media/downloads/wic_pdfs/Fasteners_DIN-EN-ISO_Standards.pdf

Last verified: 2026-10-12. Review by: 2029-10-11.
Part of [Sizes where a DIN fastener and its ISO equivalent are not interchangeable](https://referencesource.org/fastener-standard-interchangeability-exceptions/).