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Large OD Washer Dimensions (DIN 9021, M2.5 to M36)

Guide · Updated October 28, 2026

DIN 9021 covers large outside diameter flat washers, M2.5 to M36. Hole, OD and thickness agree across the HBS Solutions DIN 9021 table, the Westfield Fasteners DIN 9021 spec, the Kova DIN 9021 chart (M3 to M24) and the VIPA wide flat washer catalog (M3 to M36); min and max tolerances agree across HBS and Westfield. ISO 7093-1 is the near equivalent, not identical. Skipped: weights. Check your supplier for critical work.

Step by step

1. Pick the bolt size: Choose M2.5 to M36.
2. Read the hole: Hole d1 min is the nominal; max is the tolerance.
3. Read the OD: The OD is about three times the thread size, e.g. 30 mm at M10.
4. Check thickness: Thickness h with its min and max.
5. Choose the series: Use DIN 9021 for thin sheet, soft material or slotted holes; use ISO 7089 / DIN 125 where the hole is standard.
6. Match hardness: Use 300 HV washers with class 10.9 and higher bolts.

DIN 9021 large OD washer dimensions (mm)

Columns: thread, hole d1 min and max, OD d2 max and min, thickness h nominal, min and max.

• Thread | d1 min | d1 max | d2 max | d2 min | h | h min | h max
• M2.5 | 2.7 | 2.84 | 8 | 7.64 | 0.8 | 0.7 | 0.9
• M3 | 3.2 | 3.38 | 9 | 8.64 | 0.8 | 0.7 | 0.9
• M3.5 | 3.7 | 3.88 | 11 | 10.57 | 0.8 | 0.7 | 0.9
• M4 | 4.3 | 4.48 | 12 | 11.57 | 1 | 0.9 | 1.1
• M5 | 5.3 | 5.48 | 15 | 14.57 | 1.2 | 1 | 1.4
• M6 | 6.4 | 6.62 | 18 | 17.57 | 1.6 | 1.4 | 1.8
• M7 | 7.4 | 7.62 | 22 | 21.48 | 2 | 1.8 | 2.2
• M8 | 8.4 | 8.62 | 24 | 23.48 | 2 | 1.8 | 2.2
• M10 | 10.5 | 10.77 | 30 | 29.48 | 2.5 | 2.3 | 2.7
• M12 | 13 | 13.27 | 37 | 36.38 | 3 | 2.7 | 3.3
• M14 | 15 | 15.27 | 44 | 43.38 | 3 | 2.7 | 3.3
• M16 | 17 | 17.27 | 50 | 49.38 | 3 | 2.7 | 3.3
• M18 | 20 | 20.52 | 56 | 54.1 | 4 | 3.4 | 4.6
• M20 | 22 | 22.52 | 60 | 58.1 | 4 | 3.4 | 4.6
• M24 | 26 | 26.84 | 72 | 70.1 | 5 | 4 | 6
• M30 | 33 | 34 | 92 | 89.8 | 6 | 5 | 7
• M36 | 39 | 40 | 110 | 107.8 | 8 | 6.8 | 9.2

Worked example: M8 on thin sheet

An M8 DIN 9021 washer has an 8.4 mm hole, 24 mm OD and is 2 mm thick, versus a 16 mm OD ISO 7089 washer, more than doubling the bearing area.

Common problems

• Washer dishes under load: thickness is too thin for the preload; use a harder or thicker washer.
• Pull-through on plastic: step up to a larger OD or add a backing plate.
• ISO and DIN mixed in a bin: check thickness at M5.

FAQ

What is DIN 9021?

A plain flat washer with a large outside diameter, about three times the thread size, to spread load on thin sheet, soft material or oversized holes.

Is ISO 7093 the same?

Close but not identical. ISO 7093-1 (product grade A) is the ISO counterpart; some dimensions changed and it only has 200 HV and 300 HV hardness classes. For example, one ISO 7093-1 catalog lists M5 at 1 mm thick, where DIN 9021 is 1.2 mm.

Form A or Form B, 7093-1 or 7093-2?

ISO 7093-1 is product grade A, which is what this chart is compared against. ISO 7093-2 (product grade C) was not covered by the sources checked, so it is not charted here.

What was skipped?

Weights, and the oversize non-standard sizes some catalogs add (for example M8 x 32).

DIN 9021 vs DIN 125?

Same hole, but DIN 125 / ISO 7089 has a much smaller OD, e.g. 20 mm at M10 versus 30 mm.

Related guides and calculators

• Timber washers (DIN 1052)
• Extra large washers (ISO 7094)
• Thick washers (DIN 7349)
• Small series washers (ISO 7092 / DIN 433)
• Chamfered washers (DIN 125 B / ISO 7090)
• Tooth lock washers (DIN 6797)
• Spring lock washers (DIN 127 B)
• Serrated lock washers (DIN 6798)
• Flat washer size chart (SAE, USS, metric)
• Heavy-duty washer dimensions (DIN 7989)
• HV structural washer dimensions (DIN 6916 / ISO 7416)
• Square washer dimensions (DIN 436)
• Clamping washer dimensions (DIN 6340)
• All free machinist calculators

General shop information only — follow your drawing, tool maker's data and your quality system.