Technically reviewed by Vincent, Founder at HEXVARO
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Sourcing these sizes? Industrial washer supplier Fastener assemblies and kitting
Flat washer dimensions (mm)
Inner diameter d1 is the nominal (minimum) value; outer diameter d2 and thickness h are nominal. DIN 125-A is the plain version and DIN 125-B / ISO 7090 the chamfered version with the same main dimensions.
| Bolt size | Inner diameter d1 | Outer diameter d2 | Thickness h | Weight (kg / 1000) | Inquiry |
|---|---|---|---|---|---|
| M4 | 4.3 | 9 | 0.8 | 0.31 | Quote this size |
| M5 | 5.3 | 10 | 1 | 0.44 | Quote this size |
| M6 | 6.4 | 12 | 1.6 | 1.02 | Quote this size |
| M8 | 8.4 | 16 | 1.6 | 1.83 | Quote this size |
| M10 | 10.5 | 20 | 2 | 3.57 | Quote this size |
| M12 | 13 | 24 | 2.5 | 6.27 | Quote this size |
| M14 | 15 | 28 | 2.5 | 8.62 | Quote this size |
| M16 | 17 | 30 | 3 | 11.3 | Quote this size |
| M20 | 21 | 37 | 3 | 17.2 | Quote this size |
| M24 | 25 | 44 | 4 | 32.3 | Quote this size |
| M30 | 31 | 56 | 4 | 53.6 | Quote this size |
| M36 | 37 | 66 | 5 | 92.1 | Quote this size |
Need these DIN 125-A / ISO 7089 sizes? Request a quote
- Weights are for steel and are useful for estimating freight. Washers are light per piece but are often ordered in hundreds of thousands, so weight still adds up.
- Thickness tolerance matters for automated assembly and for preloaded joints; state it if your drawing controls it.
Hardness classes: which washer for which bolt
ISO plain washers are made in hardness classes rather than property classes. The washer must be hard enough not to sink under the bolt head or nut when the joint is tightened.
| Hardness class | Suitable for bolts up to | Suitable for nuts up to | Typical material | Inquiry |
|---|---|---|---|---|
| 140 HV | Low-strength general assembly (DIN 125 trade grade) | — | Low-carbon steel | Quote this size |
| 200 HV | Property class 8.8 | Class 8 | Steel; also stainless A2 / A4 | Quote this size |
| 300 HV | Property class 10.9 | Class 10 | Hardened and tempered steel | Quote this size |
Need these DIN 125-A / ISO 7089 sizes? Request a quote
- A soft 140 HV washer under an 8.8 or 10.9 bolt can deform and lose preload. Match the washer hardness to the bolt class.
- Hardened 300 HV washers that are electroplated should be baked to manage hydrogen embrittlement, or zinc flake coated.
- Structural preloaded bolting uses its own washer standards (EN 14399-5/-6, ASTM F436), not DIN 125.
DIN 125 vs DIN 126 vs DIN 9021
Three washer standards cover most metric bolting. They differ in hole size, outside diameter and tolerance.
| Standard | Product grade | Hole for M10 / M12 | Outside dia. for M10 / M12 | Use | Inquiry |
|---|---|---|---|---|---|
| DIN 125-A / ISO 7089 | A (fine) | 10.5 / 13 | 20 / 24 | Standard washer for bolts and screws | Quote this size |
| DIN 126 / ISO 7091 | C (coarse) | 11 / 13.5 | 20 / 24 | Construction and black bolts, larger clearance hole | Quote this size |
| DIN 9021 / ISO 7093 | A | 10.5 / 13 | 30 / 37 | Large OD for soft materials, slots and oversized holes | Quote this size |
Need these DIN 125-A / ISO 7089 sizes? Request a quote
- DIN 9021 outer diameter is about three times the bolt diameter: 18 mm for M6, 24 mm for M8, 30 mm for M10 and 37 mm for M12.
- DIN 126 has a larger hole and coarser tolerances; it suits hot-dip galvanized bolts and site work but looks loose on precision assemblies.
Finishes
- Match the washer finish to the bolt and nut. A zinc-plated washer under a hot-dip galvanized bolt will rust first and stain the steelwork.
- Hot-dip galvanized washers are thicker after coating; check the stack height for short bolts.
- Stainless A2 and A4 washers are common with stainless bolts; avoid stainless washers on galvanized steel in wet conditions unless the designer accepts it.
How to specify washers in your RFQ
- Standard: DIN 125-A / ISO 7089, DIN 125-B / ISO 7090, DIN 126 / ISO 7091 or DIN 9021 / ISO 7093.
- Bolt size, and any non-standard inner diameter, outer diameter or thickness.
- Hardness class: 140 HV, 200 HV or 300 HV, or stainless A2 / A4.
- Finish matched to the bolt and nut, with a full designation.
- Quantity per size, packaging (bags, boxes or bulk cartons) and labelling.
Order these sizes from HEXVARO
Send your size list with grade, finish and quantity — we reply within 2 working hours with price, lead time and shipping terms.
- Reply: within 2 working hours
- MOQ: 500 pcs per specification
- Lead time: 10–15 days stock items
- Payment: T/T · L/C · PayPal
- Shipping ports: Tianjin · Ningbo · Shanghai · Shenzhen
- Incoterms: EXW · FOB · CFR · CIF · DAP
- Experience: Founder with 10+ years in the fastener industry
Frequently asked questions
Is DIN 125 the same as ISO 7089?
For the sizes in this chart the inner diameter, outer diameter and thickness match. ISO 7089 is the current international standard; DIN 125-A remains the common trade name.
What is the difference between DIN 125 and DIN 9021?
DIN 9021 washers have a much larger outer diameter — about three times the bolt size — to spread load on soft or slotted materials. An M10 DIN 125 washer is 20 mm across; an M10 DIN 9021 washer is 30 mm.
Which washer hardness should I use with 10.9 bolts?
Use 300 HV hardened washers with 10.9 bolts. 200 HV washers suit bolts up to property class 8.8.
How much does an M12 flat washer weigh?
About 6.3 g in steel, or 6.27 kg per 1,000 pieces for a DIN 125-A / ISO 7089 washer.
What is the difference between DIN 125-A and DIN 125-B?
Form A is a plain washer; form B is chamfered on the outside edge. Main dimensions are the same. ISO 7090 is the chamfered ISO equivalent.
What is the MOQ for washers?
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.
Products to this standard