M5 Square Nuts are manufactured to DIN 557. This page lists the controlling dimensions for the M5 size together with the drive and the installation notes for this type.
M5 Dimensional Row (DIN 557)
| Size | Pitch (mm) | Width across flats s (mm) | Width across corners e min (mm) | Nut height m (mm) | Reference standard | Notes |
|---|---|---|---|---|---|---|
| M5 | 0.8 | 8.0 | 11.1 | 4.0 | DIN 557 / DIN 562 | Square nut, general / channel use |
Spanner & Drive for M5 Square Nuts
Drive geometry for M5 Square Nuts is given by the row above; match the tool to the listed values.
Tightening Torque for M5
| Class 8.8 (dry, ~µ 0.125) | ≈ 5.8 Nm |
|---|---|
| Class 10.9 (dry, ~µ 0.125) | ≈ 8.1 Nm |
| Class 12.9 (dry, ~µ 0.125) | ≈ 9.7 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 M5
| Tensile stress area As (ISO 898-1) | 14.2 mm² |
|---|---|
| Proof load, class 8.8 | 8.2 kN |
| Proof load, class 10.9 | 11.8 kN |
| Proof load, class 12.9 | 13.8 kN |
| Min. ultimate tensile, class 8.8 | 11.4 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.
Common Applications for M5 Square Nuts
M5 Square Nuts are commonly specified for paired with the same-size screws on PCB hardware, light enclosures and small-scale assemblies.
Mating Parts for M5
Pair M5 with the matching M5 bolt or screw, plus a M5 flat washer where required to distribute load on softer materials.
When to Step Up or Down from M5
When the joint preload approaches the proof load of M5 class 8.8, step up to M6 class 8.8 (or move to M5 class 10.9). When the joint is over-specified, M4 often saves weight and cost without losing the safety margin.
