DIN 125 A M4 Flat washer
DIN 125 A M4 is a flat washer, sized for M4 bolts. DIN version of the plain flat washer. Form A is the standard 140 HV hardness range, which is lower than the 200 HV of the ISO series.
Dimensions
- Standard
- DIN 125 A
- Type
- Flat washer
- Size
- M4
- For bolt size
- M4
- Total height h
- 0.8 mm
- Inside diameter d1
- 4.3 mm
- Outside diameter d2
- 9 mm
Nominal values in millimetres as published in DIN 125 A. Estimated weight 0.308 g per piece in steel (0.31 g in stainless), calculated from the nominal geometry — real parts vary with tolerance and head chamfers.
Other lengthsDIN 125 A M4
All M4 specificationsInterchangeability
DIN 125 A is catalogued with ISO 7089 as its equivalent designation. Dimensions are compared field by field rather than assumed identical.
Choosing and fitting this size
DIN 125 A M4 is a washer with a 4.3 mm inside diameter. It sits under a bolt head or nut to spread the clamping load; the inside diameter matches the bolt it is specified for, so the washer and fastener should always be ordered as a pair.
Hardness is the governing property rather than tensile strength: a 200 HV washer suits bolts up to class 10.9, while 140 HV washers are intended for class 8.8 and below. Using a soft washer under a high-grade bolt lets the washer deform before the bolt reaches its preload, which quietly loses clamping force.