For hex nuts, ISO 4032 defines the dimensions, tolerances and product grades. The sections below describe the scope of the document, the properties it deliberately leaves to companion standards, and the equivalent designations across standards bodies.
ISO 4032 — Scope
ISO 4032 specifies the dimensions and tolerances of hex nuts. 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 4032, alongside the related ISO 4032 / ISO 4033 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 4032
| Size | Pitch (mm) | Width across flats s (mm) | Width across corners e min (mm) | Nut height m style 1 (mm) | Nut height m style 2 (mm) | Reference standard |
|---|---|---|---|---|---|---|
| M1 | 0.25 | 2.5 | 2.71 | 0.8 | - | ISO 4032 (Style1) / ISO 4033 (Style2) |
| M1.2 | 0.25 | 3.0 | 3.28 | 1.0 | - | ISO 4032 (Style1) / ISO 4033 (Style2) |
| M1.4 | 0.3 | 3.0 | 3.28 | 1.2 | - | ISO 4032 (Style1) / ISO 4033 (Style2) |
| M1.6 | 0.35 | 3.2 | 3.48 | 1.3 | - | ISO 4032 (Style1) / ISO 4033 (Style2) |
| M2 | 0.4 | 4.0 | 4.32 | 1.6 | - | ISO 4032 (Style1) / ISO 4033 (Style2) |
| M2.5 | 0.45 | 5.0 | 5.45 | 2.0 | - | ISO 4032 (Style1) / ISO 4033 (Style2) |
| M3 | 0.5 | 5.5 | 6.01 | 2.4 | - | ISO 4032 (Style1) / ISO 4033 (Style2) |
| M3.5 | 0.6 | 6.0 | 6.58 | 2.8 | - | ISO 4032 (Style1) / ISO 4033 (Style2) |
| M4 | 0.7 | 7.0 | 7.66 | 3.2 | - | ISO 4032 (Style1) / ISO 4033 (Style2) |
| M5 | 0.8 | 8.0 | 8.79 | 4.0 | 5.0 | ISO 4032 (Style1) / ISO 4033 (Style2) |
| M6 | 1.0 | 10.0 | 11.05 | 5.0 | 6.0 | ISO 4032 (Style1) / ISO 4033 (Style2) |
| M8 | 1.25 | 13.0 | 14.38 | 6.5 | 8.0 | ISO 4032 (Style1) / ISO 4033 (Style2) |
| M10 | 1.5 | 16.0 | 17.77 | 8.0 | 10.0 | ISO 4032 (Style1) / ISO 4033 (Style2) |
| M12 | 1.75 | 18.0 | 20.03 | 10.0 | 12.0 | ISO 4032 (Style1) / ISO 4033 (Style2) |
| M14 | 2.0 | 21.0 | 23.36 | 11.0 | 14.0 | ISO 4032 (Style1) / ISO 4033 (Style2) |
| M16 | 2.0 | 24.0 | 26.75 | 13.0 | 16.0 | ISO 4032 (Style1) / ISO 4033 (Style2) |
| M18 | 2.5 | 27.0 | 29.56 | 15.0 | 18.0 | ISO 4032 (Style1) / ISO 4033 (Style2) |
| M20 | 2.5 | 30.0 | 32.95 | 16.0 | 20.0 | ISO 4032 (Style1) / ISO 4033 (Style2) |
| M22 | 2.5 | 32.0 | 35.03 | 18.0 | 22.0 | ISO 4032 (Style1) / ISO 4033 (Style2) |
| M24 | 3.0 | 36.0 | 39.55 | 19.0 | 24.0 | ISO 4032 (Style1) / ISO 4033 (Style2) |
| M27 | 3.0 | 41.0 | 45.2 | 22.0 | 27.0 | ISO 4032 (Style1) / ISO 4033 (Style2) |
| M30 | 3.5 | 46.0 | 50.85 | 24.0 | 30.0 | ISO 4032 (Style1) / ISO 4033 (Style2) |
| M33 | 3.5 | 50.0 | 55.37 | 26.0 | 33.0 | ISO 4032 (Style1) / ISO 4033 (Style2) |
| M36 | 4.0 | 55.0 | 60.79 | 29.0 | 36.0 | ISO 4032 (Style1) / ISO 4033 (Style2) |
| M39 | 4.0 | 60.0 | 66.44 | 31.0 | 39.0 | ISO 4032 (Style1) / ISO 4033 (Style2) |
| M42 | 4.5 | 65.0 | 71.3 | 34.0 | 42.0 | ISO 4032 (Style1) / ISO 4033 (Style2) |
| M45 | 4.5 | 70.0 | 76.95 | 36.0 | 45.0 | ISO 4032 (Style1) / ISO 4033 (Style2) |
| M48 | 5.0 | 75.0 | 82.6 | 38.0 | 48.0 | ISO 4032 (Style1) / ISO 4033 (Style2) |
| M52 | 5.0 | 80.0 | 88.25 | 42.0 | 52.0 | ISO 4032 (Style1) / ISO 4033 (Style2) |
| M56 | 5.5 | 85.0 | 93.56 | 45.0 | 56.0 | ISO 4032 (Style1) / ISO 4033 (Style2) |
| M60 | 5.5 | 90.0 | 99.21 | 48.0 | 60.0 | ISO 4032 (Style1) / ISO 4033 (Style2) |
| M64 | 6.0 | 95.0 | 104.86 | 51.0 | 64.0 | ISO 4032 (Style1) / ISO 4033 (Style2) |
Companion Standards
ISO 4032 controls only the geometry of hex nuts. 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 4032
Choose ISO 4032 for international engineering work and OEM supply where ISO standards are the contractual reference. It is the default modern specification for hex nuts.