Key specifications
| Standard | DIN 557, product grade C |
|---|---|
| Sizes | M5 to M20 |
| Materials | Carbon steel; stainless A2 or A4 |
| Finishes | Plain, zinc plated, plain stainless |
Made to order in China and shipped FOB or CIF from Tianjin, Ningbo, Shanghai or Shenzhen. Sizes, grades and finishes outside this list can be quoted.
Dimension drawing
DIN 557 square nut dimensions (mm)
M10 and M12 are listed with two widths across flats. Values follow the DIN 557 table.
| Size | Across flats s | Across corners e max | Height m | Inquiry |
|---|---|---|---|---|
| M5 | 8 | 11.3 | 4 | Quote this size |
| M6 | 10 | 14.1 | 5 | Quote this size |
| M8 | 13 | 18.4 | 6.5 | Quote this size |
| M10 | 16 | 22.6 | 8 | Quote this size |
| M10 | 17 | 24 | 8 | Quote this size |
| M12 | 18 | 25.4 | 10 | Quote this size |
| M12 | 19 | 26.9 | 10 | Quote this size |
| M16 | 24 | 33.9 | 13 | Quote this size |
| M20 | 30 | 42.4 | 16 | Quote this size |
Where square nuts fit
- Slots and channels, where the flats stop the nut turning.
- Timber and carriage bolt assemblies.
- Machine and agricultural assemblies built to an existing drawing.
Packing, shipping and documents
| MOQ | 500 pcs per specification; mixed sizes can be combined on one order |
|---|---|
| Lead time | 10–15 days for stock items, 25–30 days for production orders, confirmed in the quotation |
| Export packing | Inner boxes or bags labelled by size, export cartons, then palletized and stretch-wrapped; buyer labels and barcodes on request |
| Shipping ports | Tianjin, Ningbo, Shanghai, Shenzhen |
| Incoterms | EXW, FOB, CFR, CIF, DAP, DDP on request |
| HS code reference | HS 7318.16 is the usual heading for steel nuts. Confirm the final code with your customs broker. |
| Certificate of origin | ACFTA Form E available on request for buyers in ASEAN countries such as Malaysia, Indonesia, Vietnam and the Philippines |
| Order documents | Commercial invoice, packing list and inspection records agreed in the quotation |
What to include in your RFQ
- Thread size and width across flats
- Property class or material
- Finish
- Quantity per size
- Packing and destination
Frequently asked questions
What is the width across flats of an M8 square nut?
13 mm for DIN 557, with a 6.5 mm height.
Why are M10 and M12 listed twice?
DIN 557 tables list two wrench sizes for them: 16 or 17 mm for M10, and 18 or 19 mm for M12. State the one you need.
Are square nuts stronger than hex nuts?
Not as a rule. Their main benefit is that they resist turning in a slot or seat.
What is the MOQ for square nuts?
Reference MOQ is 500 pcs per specification. This product is made to order, so lead time and price are confirmed with each quotation. We reply to every RFQ within 2 working hours.
Sources for technical review