The table below lists the dimensions catalogued for square nut, metric under GB/T 39. The scope of GB/T 39 itself is not summarised here — where a figure matters, confirm it against the published document.
GB/T 39 — Scope
The table below lists the dimensions catalogued for square nut, metric — gb/t 39 / din 557 (series 076) under GB/T 39. The scope of GB/T 39 itself is not summarised here — where a figure matters, confirm it against the published document.
Tolerance & Product Grades
Product grade is a concept from dimensional fastener standards and does not apply to GB/T 39. Tolerances for this part are the limits shown against each dimension in the table.
Dimensions Specified by GB/T 39
| Size | Pitch (mm) | Width across flats s (mm) | Nut height m (mm) | Reference standard |
|---|---|---|---|---|
| M3 | 0.5 | 5.5 | 1.8 | GB/T 39 / DIN 562 |
| M4 | 0.7 | 7.0 | 2.2 | GB/T 39 / DIN 562 |
| M5 | 0.8 | 8.0 | 2.7 | GB/T 39 / DIN 562 |
| M6 | 1.0 | 10.0 | 3.6 | GB/T 39 / DIN 562 |
| M8 | 1.25 | 13.0 | 4.8 | GB/T 39 / DIN 562 |
| M10 | 1.5 | 17.0 | 6.0 | GB/T 39 / DIN 562 |
| M12 | 1.75 | 19.0 | 7.0 | GB/T 39 / DIN 562 |
| M16 | 2.0 | 24.0 | 9.0 | GB/T 39 / DIN 562 |
| M20 | 2.5 | 30.0 | 12.0 | GB/T 39 / DIN 562 |
| M24 | 3.0 | 36.0 | 14.0 | GB/T 39 / DIN 562 |
Companion Standards
A complete specification for square nut, metric — gb/t 39 / din 557 (series 076) normally cites several documents: one for the geometry, one for the material or mechanical properties, and one for the finish. GB/T 39 is one of them, not all of them.
When to Specify GB/T 39
Choose GB/T 39 for international engineering work and OEM supply where ISO standards are the contractual reference. It is the default modern specification for square nut, metric — gb/t 39 / din 557 (series 076).
Custom manufacturing · Made to drawing
Need a nut to this standard in a non-standard size?
Parts built to GB T 39 are already in the catalog, so a special is usually a variation on existing tooling rather than a new design — which is what keeps the cost down. Made by cold heading or tapping.
Minimum order from 2,000 pieces; samples within 7 days of drawing approval.
