Specification summary of DIN 938 as applied to double-end studs (din 938 / 939 / 940): the dimensions the standard controls, the tolerance and product grades it defines, the full specified size range, and the equivalent DIN/ISO/ASME designations.
DIN 938 — Scope
DIN 938 specifies the dimensions and tolerances of double-end studs (din 938 / 939 / 940). Material, property class, surface finish and packaging are governed by separate documents in the same standards family (for example ISO 898-1 for the mechanical property classes of bolts and screws).
Tolerance & Product Grades
DIN 938, alongside the related DIN 938 entries on this site, specifies product grades (typically A or B for fine work and C for general engineering) and tolerance classes for the controlling dimensions. Choose the grade against the precision your application requires.
Dimensions Specified by DIN 938
| Thread size | Metal end bm (mm) | For parent material | Nut end (mm) | Common overall length (mm) | Property class | Reference standard | Sibling standard |
|---|---|---|---|---|---|---|---|
| M8 | 8 | Steel | 8 | 30~80 | 8.8 | DIN 938 | DIN 939 = 10 mm, DIN 940 = 16 mm |
| M10 | 10 | Steel | 10 | 35~100 | 8.8 | DIN 938 | DIN 939 = 12.5 mm, DIN 940 = 20 mm |
| M12 | 12 | Steel | 12 | 40~120 | 8.8 | DIN 938 | DIN 939 = 15 mm, DIN 940 = 24 mm |
| M16 | 16 | Steel | 16 | 50~160 | 8.8 | DIN 938 | DIN 939 = 20 mm, DIN 940 = 32 mm |
| M20 | 20 | Steel | 20 | 60~200 | 8.8 | DIN 938 | DIN 939 = 25 mm, DIN 940 = 40 mm |
| M24 | 24 | Steel | 24 | 70~240 | 8.8 | DIN 938 | DIN 939 = 30 mm, DIN 940 = 48 mm |
Equivalent Standards
Where direct equivalents exist (ISO ↔ DIN, ISO ↔ ASME), they are listed on the parent Double-End Studs (DIN 938 / 939 / 940) page.
Always confirm against the dimensions on this page, since some "equivalent" standards differ in tolerances and head geometry.
Companion Standards
DIN 938 controls only the geometry of double-end studs (din 938 / 939 / 940). The mechanical strength is set by ISO 898-1 (bolts and screws) or ISO 898-2 (nuts); the surface finish is governed by separate finish standards (e.g. ISO 4042 for electroplating). For corrosion testing, the relevant document is ISO 9227 (neutral salt spray).
