For hex head bolts with reduced shank, ISO 4015 fixes the geometry and the tolerances. 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 4015 — Scope
ISO 4015 is "Hexagon head bolts — Product grade B — Reduced shank (shank diameter approximately equal to pitch diameter)". The reduced shank lets the bolt stretch under dynamic load; the full-shank equivalent is ISO 4014.
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
ISO 4015 is written to product grade B; a different grade of the same part is a different document in the family, not a variant of this one.
Dimensions Specified by ISO 4015
| Size | Pitch P (mm) | b1 (mm) | b2 (mm) | c_max (mm) | d_a_max (mm) | d_s (mm) | d_w_min (mm) | Width across corners e (mm) | Head height k (mm) | k_max (mm) | k_min (mm) | k_w_min (mm) | r_min (mm) | Width across flats s (mm) | s_min (mm) | x_max (mm) | Length range l (mm) | Reference standard |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| M3 | 0.5 | 12 | 0 | 0.4 | 3.6 | 2.6 | 4.72 | 5.88 | 2 | 2.2 | 1.8 | 1.26 | 0.1 | 5.5 | 5.2 | 1.25 | 20~30 | ISO 4015 |
| (M3.5) | 0.6 | 13 | 0 | 0.4 | 4.1 | 3.05 | 5.22 | 6.44 | 2.4 | 2.6 | 2.2 | 1.54 | 0.1 | 6 | 5.7 | 1.5 | 20~35 | ISO 4015 |
| M4 | 0.7 | 14 | 0 | 0.4 | 4.7 | 3.5 | 6.06 | 7.5 | 2.8 | 3 | 2.6 | 1.82 | 0.2 | 7 | 6.64 | 1.75 | 20~40 | ISO 4015 |
| M5 | 0.8 | 16 | 0 | 0.5 | 5.7 | 4.4 | 7.06 | 8.63 | 3.5 | 3.74 | 3.26 | 2.28 | 0.2 | 8 | 7.64 | 2 | 25~50 | ISO 4015 |
| M6 | 1 | 18 | 0 | 0.5 | 6.8 | 5.3 | 8.74 | 10.89 | 4 | 4.24 | 3.76 | 2.63 | 0.25 | 10 | 9.64 | 2.5 | 25~60 | ISO 4015 |
| (M7) | 1 | 20 | 0 | 0.6 | 7.8 | 6.2 | 9.47 | 11.94 | 4.8 | 5.04 | 4.56 | 3.19 | 0.25 | 11 | 10.57 | 2.5 | 30~70 | ISO 4015 |
| M8 | 1.25 | 22 | 0 | 0.6 | 9.2 | 7.1 | 11.47 | 14.2 | 5.3 | 5.54 | 5.06 | 3.54 | 0.4 | 13 | 12.57 | 3.2 | 30~80 | ISO 4015 |
| M10 | 1.5 | 26 | 0 | 0.6 | 11.2 | 8.9 | 14.97 | 17.59 | 6.9 | 6.69 | 6.11 | 4.28 | 0.4 | 16 | 15.57 | 3.8 | 40~100 | ISO 4015 |
| M12 | 1.75 | 30 | 0 | 0.6 | 13.7 | 10.7 | 16.47 | 19.85 | 7.5 | 7.79 | 7.21 | 5.05 | 0.6 | 18 | 17.57 | 4.3 | 45~120 | ISO 4015 |
| (M14) | 2 | 34 | 40 | 0.6 | 15.7 | 12.5 | 19.15 | 22.78 | 8.8 | 9.09 | 8.51 | 5.96 | 0.6 | 21 | 20.16 | 5 | 50~140 | ISO 4015 |
| M16 | 2 | 38 | 44 | 0.8 | 17.7 | 14.5 | 22 | 26.17 | 10 | 10.29 | 9.71 | 6.8 | 0.6 | 24 | 23.16 | 5 | 55~150 | ISO 4015 |
| (M18) | 2.5 | 42 | 48 | 0.8 | 20.2 | 16.3 | 24.85 | 29.56 | 11.5 | 11.85 | 11.15 | 7.81 | 0.6 | 27 | 26.16 | 6.3 | 60~150 | ISO 4015 |
| M20 | 2.5 | 46 | 52 | 0.8 | 22.4 | 18.2 | 27.7 | 32.95 | 12.5 | 12.85 | 12.15 | 8.51 | 0.8 | 30 | 29.16 | 6.3 | 65~150 | ISO 4015 |
Equivalent Standards
Where direct equivalents exist (ISO ↔ DIN, ISO ↔ ASME), they are listed on the parent Hex Head Bolts with Reduced Shank page.
Always confirm against the dimensions on this page, since some "equivalent" standards differ in tolerances and head geometry.
Companion Standards
ISO 4015 controls only the geometry of hex head bolts with reduced shank. 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).
Custom manufacturing · Made to drawing
Need a bolt to this standard in a non-standard size?
Parts built to ISO 4015 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 hot forging.
Minimum order from 2,000 pieces; samples within 7 days of drawing approval.
