Fastener Size Chart
Use this reference chart to quickly identify the correct brass fastener size for your application. Covers all major fastener types in metric and imperial sizes.
Brass Bolt & Screw Sizes
Brass bolts and screws are available from M2 to M36 in metric sizes and #2 to 3/4" in UNC/UNF. Head types include hex, socket cap, pan, countersunk and round head.
| Size | Thread Pitch (mm) | Head Width (mm) | Standard |
|---|---|---|---|
| M3 | 0.5 | 5.5 | DIN 933 / ISO 4017 |
| M4 | 0.7 | 7.0 | DIN 933 / ISO 4017 |
| M5 | 0.8 | 8.0 | DIN 933 / ISO 4017 |
| M6 | 1.0 | 10.0 | DIN 933 / ISO 4017 |
| M8 | 1.25 | 13.0 | DIN 933 / ISO 4017 |
| M10 | 1.5 | 17.0 | DIN 933 / ISO 4017 |
| M12 | 1.75 | 19.0 | DIN 933 / ISO 4017 |
| M16 | 2.0 | 24.0 | DIN 933 / ISO 4017 |
| M20 | 2.5 | 30.0 | DIN 933 / ISO 4017 |
Brass Nut Sizes
Brass hex nuts are manufactured to DIN 934 / ISO 4032 standards. Available from M2 to M36.
| Size | Width Across Flats (mm) | Height (mm) | Standard |
|---|---|---|---|
| M3 | 5.5 | 2.4 | DIN 934 / ISO 4032 |
| M4 | 7.0 | 3.2 | DIN 934 / ISO 4032 |
| M5 | 8.0 | 4.0 | DIN 934 / ISO 4032 |
| M6 | 10.0 | 5.0 | DIN 934 / ISO 4032 |
| M8 | 13.0 | 6.5 | DIN 934 / ISO 4032 |
| M10 | 17.0 | 8.0 | DIN 934 / ISO 4032 |
| M12 | 19.0 | 10.0 | DIN 934 / ISO 4032 |
| M16 | 24.0 | 13.0 | DIN 934 / ISO 4032 |
| M20 | 30.0 | 16.0 | DIN 934 / ISO 4032 |
Brass Washer Sizes
Brass flat washers to DIN 125 / ISO 7089. Available in narrow, standard and wide series.
| Bolt Size | Inner Dia (mm) | Outer Dia (mm) | Thickness (mm) |
|---|---|---|---|
| M3 | 3.2 | 7.0 | 0.5 |
| M4 | 4.3 | 9.0 | 0.8 |
| M5 | 5.3 | 10.0 | 1.0 |
| M6 | 6.4 | 12.0 | 1.6 |
| M8 | 8.4 | 16.0 | 1.6 |
| M10 | 10.5 | 20.0 | 2.0 |
| M12 | 13.0 | 24.0 | 2.5 |
| M16 | 17.0 | 30.0 | 3.0 |
| M20 | 21.0 | 37.0 | 3.0 |
Frequently Asked Questions
What is the most common brass fastener size?
M6 and M8 are the most commonly used brass fastener sizes across plumbing, electrical and general industrial applications.
Do you supply custom sizes not listed in the chart?
Yes. RKIC Group manufactures custom brass fasteners in non-standard sizes. Contact our technical team with your specifications.
Need Technical Assistance?
Our technical team is available Mon–Fri, 9AM–6PM for fastener selection and application engineering.