referencesource/fastener-standard-interchangeability-exceptions

Sizes where a DIN fastener and its ISO equivalent are not interchangeable

Canonical, always-current version: https://referencesource.org/fastener-standard-interchangeability-exceptions/ Machine-readable: https://referencesource.org/fastener-standard-interchangeability-exceptions/data.json — this mirror is a point-in-time copy.

• Last verified: 2026-10-12
• Stale after: 2029-10-11 (past this date, prefer the canonical copy — it re-verifies on a cadence this snapshot does not)
• Records: 140

The specific thread sizes at which a withdrawn DIN fastener standard and its current ISO counterpart give DIFFERENT dimensions, so the two parts are not simply interchangeable. Each record is one size at which one named dimension differs between the two standards, with both published values side by side -- or, for two standard pairs, the publisher's own interchangeability verdict in its own words. Answers 'is DIN 933 the same as ISO 4017', 'DIN 934 vs ISO 4032 nut height', 'my drawing says DIN 931 and my distributor only stocks ISO 4014', and 'will my spanner still fit'. The headline DIN-to-ISO crossover mapping is easy, everyone publishes it, and it is NOT here: the sibling dataset fastener-thread-standard-equivalence owns that and states it from five publishers. What is here is the exception detail, where free sources fail and contradict each other. Wurth prints four sizes at which the width across flats changed between DIN 933 and ISO 4017 -- M10 17 mm becomes 16 mm, M12 19 becomes 18, M14 22 becomes 21, M22 32 becomes 34, meaning a different spanner -- while Monster Bolts lists that same pair as 'Fully interchangeable'. That disagreement is the fact, and it is published in full on the sibling's DIN 933 page, which carries both publishers' verdicts side by side and is linked from every page here. What this dataset adds is the sizes at which the blanket verdict fails. 16 standard pairs carry size-level divergences, across head diameter, head height, nut height, slot width and width across flats. Note that M22 goes UP, not down, so 'ISO is one size smaller' is a wrong rule of thumb.

Provenance — what every record carries

Every record carries source (the URL the value was read from) and source_quote (a verbatim quote from that page stating it). A value you cannot check against its page is indistinguishable from an invented one; these can all be checked. Each record is also individually addressable on the canonical site at its url.

Licence position

Facts extracted from freely published distributor technical pages. Dimensions are facts, not copyrightable expression (US: Feist, 1991). ISO 4017 and the other ISO fastener documents were not purchased or opened; ISO's own terms restrict use of ISO content, and no ISO content is used here -- only dimensions as facts, quoted from distributors who published them. Of Wurth Industry of Canada's booklet only the rows where two standards DIFFER were taken -- 134 rows out of several thousand cells printed -- so what is reproduced is the divergence, not the compilation. The Monster Bolts and TR Fastenings mapping rows were removed from this asset on 2026-10-16 as duplicates of fastener-thread-standard-equivalence; Monster Bolts' interchangeability verdict is quoted in the description and published in the sibling.

Facts are not copyrightable; what this dataset takes from each source is a fact plus a short attributed quote linking back to the page that states it.

Sources

• https://www.wurthindustry.ca/media/downloads/wic_pdfs/Fasteners_DIN-EN-ISO_Standards.pdf
• https://www.wuerth.de/web/de/awkg/kompetenz/din_iso_normteile/din-933-931-iso-4014-4017-sechskantschrauben.php

Fields

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