M12 Stud (GB/T 15389 / DIN 939) are specified by thread size, length and head dimensions. The M12 row from the standard is reproduced below, followed by the drill sizes, spanner size and torque values used when installing this size.
M12 Dimensional Row (GB/T 15389 / DIN 939)
| Thread size | Pitch (mm) | Length L (mm) | Engagement depth bm (mm) | Material | Reference standard |
|---|---|---|---|---|---|
| M12 | 1.75 | 100 | 18 | Cl. 8.8 alloy steel | DIN 939 / GB/T 901 |
Spanner & Drive for M12 Stud — GB/T 15389 / DIN 939 (Series 096)
Drive geometry for M12 Stud — GB/T 15389 / DIN 939 (Series 096) is given by the row above; match the tool to the listed values.
Hole Sizes for M12
| Coarse-thread pitch (ISO 724) | 1.75 mm |
|---|---|
| Through-hole / clearance (ISO 273 medium) | 13.5 mm |
| Tapping drill, coarse thread | 10.2 mm |
Tightening Torque for M12
| Class 8.8 (dry, ~µ 0.125) | ≈ 85 Nm |
|---|---|
| Class 10.9 (dry, ~µ 0.125) | ≈ 120 Nm |
| Class 12.9 (dry, ~µ 0.125) | ≈ 145 Nm |
Indicative dry-joint values. Lubrication can lower the required torque by 15–25%. Always confirm against the joint design, especially when going up a strength class.
Proof Load & Strength for M12
| Tensile stress area As (ISO 898-1) | 84.3 mm² |
|---|---|
| Proof load, class 8.8 | 49 kN |
| Proof load, class 10.9 | 70 kN |
| Proof load, class 12.9 | 82 kN |
| Min. ultimate tensile, class 8.8 | 67 kN |
Proof load = stress area × proof stress per ISO 898-1. Design joints so the working preload stays below the proof load of the selected class.
M12 Stud — GB/T 15389 / DIN 939 (Series 096) Weight
A steel M12 stud at the listed 100 mm length weighs approximately 89 g each — about 89 kg per 1,000 pieces. Stainless A2/A4 weighs roughly the same (density 7.9–8.0 g/cm³). Actual weight varies slightly with head form, thread and finish; use this figure for freight estimation only.
Common Applications for M12 Stud — GB/T 15389 / DIN 939 (Series 096)
M12 Stud — GB/T 15389 / DIN 939 (Series 096) are commonly specified for medium-duty structural connections, automotive sub-frames and equipment chassis.
Mating Parts for M12
For M12, pair with a M12 hex nut (ISO 4032 / DIN 934) and, where used, a M12 flat washer (ISO 7089 / DIN 125A) under the head and under the nut.
When to Step Up or Down from M12
When the joint preload approaches the proof load of M12 class 8.8, step up to M16 class 8.8 (or move to M12 class 10.9). When the joint is over-specified, M10 often saves weight and cost without losing the safety margin.