DIN 939 is the governing dimensional standard for thin hex nut. This page sets out the scope of the standard, reproduces the full size table it specifies, and lists the DIN/ISO/ASME cross-references commonly cited in datasheets and drawings.
DIN 939 — Scope
DIN 939 is "Double end studs — Metal end 1.25 d".
Material, property class, surface finish and packaging are governed by separate documents — ISO 898-1 and ISO 898-2 for mechanical property classes, ISO 4042 for electroplated finishes.
Tolerance & Product Grades
DIN 939 does not divide thin hex nut — gb/t 901 / din 939 (series 094) into product grades. Tolerances are given as limits on the individual dimensions in the table.
Where a general-tolerance class is cited on the drawing instead, it applies to the dimensions not otherwise toleranced.
Dimensions Specified by DIN 939
| Size | Pitch (mm) | Width across flats s (mm) | Width across corners e (mm) | Nut height m (mm) | Reference standard |
|---|---|---|---|---|---|
| M3 | 0.5 | 5.5 | 6.01 | 1.8 | ISO 4035 / GB/T 6172 |
| M4 | 0.7 | 7.0 | 7.66 | 2.2 | ISO 4035 / GB/T 6172 |
| M5 | 0.8 | 8.0 | 8.79 | 2.7 | ISO 4035 / GB/T 6172 |
| M6 | 1.0 | 10.0 | 11.05 | 3.2 | ISO 4035 / GB/T 6172 |
| M8 | 1.25 | 13.0 | 14.38 | 4.0 | ISO 4035 / GB/T 6172 |
| M10 | 1.5 | 16.0 | 17.77 | 5.0 | ISO 4035 / GB/T 6172 |
| M12 | 1.75 | 18.0 | 20.03 | 6.0 | ISO 4035 / GB/T 6172 |
| M14 | 2.0 | 21.0 | 23.36 | 7.0 | ISO 4035 / GB/T 6172 |
| M16 | 2.0 | 24.0 | 26.75 | 8.0 | ISO 4035 / GB/T 6172 |
| M18 | 2.5 | 27.0 | 30.14 | 9.0 | ISO 4035 / GB/T 6172 |
| M20 | 2.5 | 30.0 | 33.53 | 10.0 | ISO 4035 / GB/T 6172 |
| M24 | 3.0 | 36.0 | 39.98 | 12.0 | ISO 4035 / GB/T 6172 |
| M30 | 3.5 | 46.0 | 50.85 | 15.0 | ISO 4035 / GB/T 6172 |
| M36 | 4.0 | 55.0 | 60.79 | 18.0 | ISO 4035 / GB/T 6172 |
Companion Standards
DIN 939 controls only the geometry of thin hex nut — gb/t 901 / din 939 (series 094). The mechanical strength is set by ISO 898-1 (bolts, screws and studs) or ISO 898-2 (nuts); the surface finish is governed by separate finish standards such as ISO 4042 for electroplating. For corrosion testing, the relevant document is ISO 9227 (neutral salt spray).
When to Specify DIN 939
DIN 939 is still widely used in European mechanical engineering and as a cross-reference on legacy drawings; its ISO equivalent is preferred for new designs.
Custom manufacturing · Made to drawing
Need a nut to this standard in a non-standard size?
Parts built to DIN 939 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.
