DIN / GB / ISO Fastener Cross-Reference Chart | Purchase Matching Guide
The most common confusion in export trade: drawings say DIN, factories produce to GB, inspectors cite ISO. This chart covers the DIN-GB-ISO equivalents for the most-used bolts and nuts (e.g. hex bolt fully threaded DIN 933 = GB/T 5783 = ISO 4017), plus notes on across-flats differences and superseded standards.
Common Bolt Standards
When the drawing says DIN but the quotation is ISO or GB, match directly with the table below. The full chart (including ANSI/ASME inch series) is available on request.
| Product | DIN (German) | GB (Chinese) | ISO |
|---|---|---|---|
| Hex bolt, fully threaded | DIN 933 | GB/T 5783 | ISO 4017 |
| Hex bolt, partially threaded | DIN 931 | GB/T 5782 | ISO 4014 |
| Socket head cap screw | DIN 912 | GB/T 70.1 | ISO 4762 |
| Hex flange bolt | DIN 6921 | GB/T 5787 | ISO 15072 |
| Hex bolt, reduced shank class B | DIN 961 | GB/T 5784 | ISO 8765 |
| Round head square neck bolt (carriage bolt) | DIN 603 | GB/T 12 | — |
Common Nut Standards
| Product | DIN (German) | GB (Chinese) | ISO |
|---|---|---|---|
| Type 1 hex nut, coarse thread | DIN 934 | GB/T 6170 | ISO 4032 |
| Type 2 hex nut, coarse thread | DIN 934 (heavy) | GB/T 6175 | ISO 4033 |
| Type 1 hex nut, fine thread | DIN 934M (fine) | GB/T 6176 | ISO 8673 |
| Hex flange nut | DIN 6923 | GB/T 6177 | ISO 4161 |
| Nylon-insert lock nut | DIN 985 | GB/T 889 | ISO 10511 |
| Acorn / cap nut | DIN 1587 | GB/T 923 | — |
Three Points to Watch
Across-flats differences: an M10 hex nut DIN 934 is 17 mm A/F and ISO 4032 is also 17 mm, but an M10 flange nut (DIN 6923) is 15 mm - same name, different part; always match by standard number, not just size.
M12 across-flats: new DIN/ISO editions give 18 mm A/F for M12 hex parts while older drawings show 19 mm; both are producible - state which one in the quotation.
Superseded standards: some DIN standards are replaced by DIN EN ISO (e.g. DIN 933 → ISO 4017) with equivalent performance; supplying to the old DIN per legacy drawings is fine, but confirm the inspection standard with the customer upfront.
Frequently Asked Questions
The three dimension systems basically correspond (DIN 933 → ISO 4017 → GB/T 5783); property classes are separately marked per GB/T 3098.1 / ISO 898-1. The key is to state the full executing standard in the quotation and contract, and confirm the inspection standard upfront to avoid disputes at destination.
An M10 flange nut (DIN 6923) is 15 mm across flats versus 17 mm for a Type 1 hex nut (DIN 934) - the flange takes over part of the bearing function. Always cross-check the standard number, not just the size.
This chart covers the most-used metric standards from daily export orders. The complete chart including the inch ANSI/ASME series is available on request; for US-standard flange stud pairing see our ASTM A193 B7 / A194 2H article.
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