Specification summary of ISO 12126 as applied to fine-thread all-metal hex flange lock nuts: the dimensions the standard controls, the full specified size range, and the equivalent DIN/ISO/ASME designations.
ISO 12126 — Scope
ISO 12126 is "Prevailing torque type all-metal hexagon nuts with flange with metric fine pitch thread".
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 12126 does not divide fine-thread all-metal hex flange lock nuts 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 ISO 12126
| Size | Pitch P (mm) | c (mm) | d_a_max (mm) | d_a_min (mm) | d_c_max (mm) | d_w_min (mm) | Width across corners e (mm) | h_max (mm) | h_min (mm) | m_min (mm) | m_w_min (mm) | Width across flats s (mm) | s_min (mm) | r_max (mm) | Reference standard |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| M8x1 | 1 | 1.2 | 8.75 | 8 | 17.9 | 15.8 | 14.38 | 9.4 | 8.74 | 7.64 | 4.6 | 13 | 12.73 | 0.5 | ISO 12126 |
| M10x1 | 1 | 1.5 | 10.8 | 10 | 21.8 | 19.6 | 16.64 | 11.4 | 10.34 | 9.64 | 5.6 | 15 | 14.73 | 0.6 | ISO 12126 |
| (M10x1.25) | 1.25 | 1.5 | 10.8 | 10 | 21.8 | 19.6 | 16.64 | 11.4 | 10.34 | 9.64 | 5.6 | 15 | 14.73 | 0.6 | ISO 12126 |
| M12x1.5 | 1.5 | 1.8 | 13 | 12 | 26 | 23.8 | 20.03 | 13.8 | 12.57 | 11.57 | 6.8 | 18 | 17.73 | 0.7 | ISO 12126 |
| (M12x1.25) | 1.25 | 1.8 | 13 | 12 | 26 | 23.8 | 20.03 | 13.8 | 12.57 | 11.57 | 6.8 | 18 | 17.73 | 0.7 | ISO 12126 |
| (M14x1.5) | 1.5 | 2.1 | 15.1 | 14 | 29.9 | 27.6 | 23.36 | 15.9 | 14.8 | 13.3 | 7.7 | 21 | 20.67 | 0.9 | ISO 12126 |
| M16x1.5 | 1.5 | 2.4 | 17.3 | 16 | 34.5 | 31.9 | 26 | 18.3 | 17.2 | 15.3 | 8.9 | 24 | 23.67 | 1 | ISO 12126 |
| M20x1.5 | 1.5 | 3 | 21.6 | 20 | 42.8 | 39.9 | 32.95 | 22.4 | 20.3 | 18.7 | 10.7 | 30 | 29.16 | 1.2 | ISO 12126 |
Equivalent Standards
Where direct equivalents exist (ISO ↔ DIN, ISO ↔ ASME), they are listed on the parent Fine-Thread All-Metal Hex Flange Lock Nuts page.
Always confirm against the dimensions on this page, since some "equivalent" standards differ in tolerances and head geometry.
Companion Standards
ISO 12126 controls only the geometry of fine-thread all-metal hex flange lock nuts. 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 nut to this standard in a non-standard size?
Parts built to ISO 12126 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.
