M6 Washer Dimensions & Size

Q: What does the “M6” designation mean on a washer?

The “M” stands for Metric, and the number represents the nominal thread diameter of the screw or bolt. An M6 washer is designed specifically for fasteners with a 6 mm nominal major diameter.

Q: What is the difference between Form A and Form B washers?

The difference lies in the outer edge finish. Form A washers have a square, flat edge and are the most common. Form B washers include a 30° to 40° chamfer (beveled edge) on one side, according to DIN 125B and ISO 7090 standards.

Q: When should I use a Large Series (DIN 9021) M6 washer?

The Large Series (DIN 9021 / ISO 7093) features a significantly wider outside diameter—exactly three times the nominal thread size (18mm). Use this when fastening into soft materials like wood, plastic, or thin composites where the clamping force needs to be distributed over a maximum surface area to prevent pull-through.

Q: What does the HV rating mean on a washer?

HV stands for Vickers Hardness. For M6 fasteners, a rating of 200 HV or 300 HV is standard for steel and stainless steel. This ensures the washer maintains its flatness and resists indentation when tightened to the torque levels required for structural mechanical fastening.

Q: What is the difference between Small Series (DIN 433) and Normal Series?

The Small Series (DIN 433 / ISO 7092) has a narrower outside diameter (11mm) compared to the Normal Series (12mm). It is designed for use where space is highly restricted or when using Socket Head Cap Screws where the washer must fit within a tight counterbore.

Q: In which materials are M6 washers commonly available?

M6 washers are most frequently produced in A2 (304) and A4 (316) Stainless Steel for corrosion resistance. They are also widely available in Zinc-Plated Steel for cost-effective general hardware and Nylon for non-conductive and anti-vibration applications.

M6 washer dimensions are standardized for a broad range of structural and mechanical applications, including automotive framing, industrial machinery, office furniture assembly, and architectural hardware. Specifically designed for fasteners with a 6 mm nominal diameter, these components ensure stable load distribution and protect mating surfaces from damage during tightening. This chart covers Form A plain washers, which feature a flat surface without a chamfer (unlike Form B).

The M6 size is a highly versatile industrial standard available in three series: the Normal Series (DIN 125A / ISO 7089) for standard load distribution, the Large Series (DIN 9021 / ISO 7093) for increased surface area, and the Small Series (DIN 433 / ISO 7092) for tight clearances. Based on these standards, M6 washers typically feature a hardness of 200 HV or 300 HV (Vickers Hardness), providing the structural integrity required to prevent deformation or “cupping” under the significant clamping forces generated by M6 bolts.

Note: While these values reflect standard manufacturer datasheets, actual dimensions and tolerances may vary based on material (e.g., Stainless Steel vs. Nylon) and manufacturing class. Always verify with the official product datasheet for critical applications.

Washer dimension diagram showing inner diameter, outside diameter, and thickness

M6 Standard Series Washer – DIN 125A/ISO 7089
Dimension	Size (mm)
Dimension	Min	Max
Inner Diameter	6.4	6.62
Outside Diameter	11.57	12
Thickness	1.4	1.8

M6 Large Series Washer – DIN 9021/ISO 7093
Dimension	Size (mm)
Dimension	Min	Max
Inner Diameter	6.4	6.62
Outside Diameter	17.57	18
Thickness	1.4	1.8

M6 Small Series Washer – DIN 433/ISO 7092
Dimension	Size (mm)
Dimension	Min	Max
Inner Diameter	6.4	6.62
Outside Diameter	10.57	11
Thickness	1.4	1.8

Inner Diameter – The diameter of the hole, designed to clear the bolt/screw thread.
Outside Diameter – The total width of the washer, determining the load distribution area.
Thickness – The height of the washer, providing the spacing and structural support.

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Frequently Asked Questions

What does the “M6” designation mean on a washer?

The “M” stands for Metric, and the number represents the nominal thread diameter of the screw or bolt. An M6 washer is designed specifically for fasteners with a 6 mm nominal major diameter.

What is the difference between Form A and Form B washers?

The difference lies in the outer edge finish. Form A washers have a square, flat edge and are the most common. Form B washers include a 30° to 40° chamfer (beveled edge) on one side, according to DIN 125B and ISO 7090 standards.

When should I use a Large Series (DIN 9021) M6 washer?

The Large Series (DIN 9021 / ISO 7093) features a significantly wider outside diameter—exactly three times the nominal thread size (18mm). Use this when fastening into soft materials like wood, plastic, or thin composites where the clamping force needs to be distributed over a maximum surface area to prevent pull-through.

What does the HV rating mean on a washer?

HV stands for Vickers Hardness. For M6 fasteners, a rating of 200 HV or 300 HV is standard for steel and stainless steel. This ensures the washer maintains its flatness and resists indentation when tightened to the torque levels required for structural mechanical fastening.

What is the difference between Small Series (DIN 433) and Normal Series?

The Small Series (DIN 433 / ISO 7092) has a narrower outside diameter (11mm) compared to the Normal Series (12mm). It is designed for use where space is highly restricted or when using Socket Head Cap Screws where the washer must fit within a tight counterbore.

In which materials are M6 washers commonly available?

M6 washers are most frequently produced in A2 (304) and A4 (316) Stainless Steel for corrosion resistance. They are also widely available in Zinc-Plated Steel for cost-effective general hardware and Nylon for non-conductive and anti-vibration applications.