Technically reviewed by Vincent, Founder at HEXVARO
Last reviewed
The short answer
| Question | Answer |
|---|---|
| Same product type? | Yes — hexagon head bolt (screw) threaded to the head |
| Same thread? | Yes — ISO metric coarse thread, same pitch |
| Same head size? | Yes, except width across flats on M10, M12, M14 and M22 |
| Which is current? | ISO 4017:2022; DIN 933 is withdrawn |
| Interchangeable? | Usually yes, with buyer approval; check the four sizes and any tooling or packaging that depends on the spanner size |
Where DIN 933 and ISO 4017 differ (mm)
Only the width across flats (spanner size) changes in these four sizes. Head height and thread are unchanged for practical ordering.
| Size | Width across flats — DIN 933 | Width across flats — ISO 4017 | Difference |
|---|---|---|---|
| M10 | 17 | 16 | ISO 1 mm smaller |
| M12 | 19 | 18 | ISO 1 mm smaller |
| M14 | 22 | 21 | ISO 1 mm smaller |
| M22 | 32 | 34 | ISO 2 mm larger |
- M12 is the size where buyers most often notice the change: a 19 mm socket is loose on an 18 mm ISO head.
- The same four sizes change between DIN 934 and ISO 4032 nuts, so mixed DIN and ISO bolts and nuts need two spanners.
- Automated tightening tools, socket trays and fixtures designed for one standard may not fit the other.
What stays the same
- Property classes come from ISO 898-1 in both cases (4.6, 4.8, 8.8, 10.9, 12.9) and stainless grades from ISO 3506 (A2-70, A4-80).
- Thread pitch, nominal lengths and the fact that the bolt is threaded to the head.
- Coatings are specified separately (e.g. ISO 4042 zinc plating, ISO 10684 hot-dip galvanizing, ISO 10683 zinc flake), whichever product standard is used.
- The partial-thread equivalent pair is DIN 931 and ISO 4014, with the same four spanner-size changes.
When substitution is fine — and when to ask first
| Situation | Recommendation |
|---|---|
| Sizes other than M10, M12, M14, M22 | Normally interchangeable; still record the accepted standard on the order |
| M10, M12, M14 or M22 assembled by hand | Usually acceptable if the user has the right spanner; confirm with the buyer |
| Automated or torque-controlled assembly | Ask first: sockets, nut runners and fixtures are sized to one standard |
| Drawing or customer contract names DIN 933 | Quote DIN 933, or list ISO 4017 as an alternative needing written approval |
| Distributor stock and resale | Label the standard clearly on cartons so the end user receives what the label says |
How to word the RFQ and the order
- Write one governing standard per line: "DIN 933 M12 × 50 8.8 zinc plated" or "ISO 4017 M12 × 50 8.8 zinc plated".
- If either is acceptable, say so: "DIN 933 or ISO 4017 accepted; state which is supplied".
- For M10, M12, M14 and M22, state the required width across flats if it matters.
- Add property class, finish, quantity per size, packaging and the certificate you need (e.g. EN 10204 3.1).
- Make sure carton labels and the certificate show the standard actually supplied.
Ordering full-thread bolts from HEXVARO
Use the full-thread product page link below to start a pre-filled Request a Quote, or send your size list. HEXVARO supplies fasteners made in Hebei and Anhui, China. Reference MOQ is 500 pcs per specification; stock sizes typically ship in 10–15 days and made-to-order sizes in 25–30 days, subject to quotation. We reply to every RFQ within 2 working hours.
Frequently asked questions
Is DIN 933 the same as ISO 4017?
Nearly. Both are full-thread hex bolts with the same thread and most head dimensions, but the spanner size differs for M10 (17 vs 16 mm), M12 (19 vs 18 mm), M14 (22 vs 21 mm) and M22 (32 vs 34 mm).
Is DIN 933 still valid?
DIN 933 has been withdrawn and replaced by ISO 4017 (DIN EN ISO 4017 in Germany). The DIN number is still widely used as a product name.
What wrench size is an M12 ISO 4017 bolt?
18 mm. The DIN 933 version uses 19 mm.
Can I mix DIN 933 bolts with ISO 4032 nuts?
Yes, the threads match. For M10, M12, M14 and M22 the bolt and nut will need different spanners.
What is the difference between DIN 933 and DIN 931?
DIN 933 (ISO 4017) is threaded to the head; DIN 931 (ISO 4014) has a plain shank and partial thread. See our DIN 931 vs DIN 933 guide.