ISO 4016 is the international standard for hex bolts, grade c. This page sets out what the standard governs, the size range it specifies, and the related standards you will see referenced in datasheets.
ISO 4016 — Scope
ISO 4016 specifies the dimensions and tolerances of hex bolts, grade c. 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
ISO 4016, alongside the related ISO 4016 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 ISO 4016
| Size | Pitch (mm) | Width across flats s (mm) | Width across corners e min (mm) | Head height k (mm) | Product grade | Reference standard |
|---|---|---|---|---|---|---|
| M5 | 0.8 | 8.0 | 8.63 | 3.35 | Grade C | ISO 4016 / DIN 601 |
| M6 | 1.0 | 10.0 | 10.89 | 4.15 | Grade C | ISO 4016 / DIN 601 |
| M8 | 1.25 | 13.0 | 14.2 | 5.45 | Grade C | ISO 4016 / DIN 601 |
| M10 | 1.5 | 17.0 | 18.72 | 6.58 | Grade C | ISO 4016 / DIN 601 |
| M12 | 1.75 | 19.0 | 20.88 | 7.68 | Grade C | ISO 4016 / DIN 601 |
| M14 | 2.0 | 22.0 | 24.49 | 9.25 | Grade C | ISO 4016 / DIN 601 |
| M16 | 2.0 | 24.0 | 26.75 | 10.18 | Grade C | ISO 4016 / DIN 601 |
| M18 | 2.5 | 27.0 | 29.56 | 11.72 | Grade C | ISO 4016 / DIN 601 |
| M20 | 2.5 | 30.0 | 33.53 | 12.72 | Grade C | ISO 4016 / DIN 601 |
| M22 | 2.5 | 32.0 | 35.72 | 14.5 | Grade C | ISO 4016 / DIN 601 |
| M24 | 3.0 | 36.0 | 39.55 | 15.35 | Grade C | ISO 4016 / DIN 601 |
| M27 | 3.0 | 41.0 | 45.2 | 17.92 | Grade C | ISO 4016 / DIN 601 |
| M30 | 3.5 | 46.0 | 50.85 | 19.75 | Grade C | ISO 4016 / DIN 601 |
| M36 | 4.0 | 55.0 | 60.79 | 23.35 | Grade C | ISO 4016 / DIN 601 |
| M42 | 4.5 | 65.0 | 71.3 | 27.05 | Grade C | ISO 4016 / DIN 601 |
| M48 | 5.0 | 75.0 | 82.6 | 31.07 | Grade C | ISO 4016 / DIN 601 |
Companion Standards
ISO 4016 controls only the geometry of hex bolts, grade c. 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).
When to Specify ISO 4016
Choose ISO 4016 for international engineering work and OEM supply where ISO standards are the contractual reference. It is the default modern specification for hex bolts, grade c.