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Curved Spring Washer Dimensions (DIN 128 Form A, M2 to M36)
Guide · Updated October 28, 2026
DIN 128 covers curved (form A) and waved (form B) split spring washers; this chart is form A, M2 to M36. Hole, section width, thickness and free height agree across the fasteners.eu DIN 128 A table, the Aspen Fasteners DIN 128 spec and the Filtomatic DIN 128 sheet; OD agrees across Aspen, Filtomatic and the Wegertseder form A sheet (M3 to M20). Skipped: form B, weights and the M7 OD. Check your supplier for critical work.
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Step by step
- Pick the size: Choose by thread, M2 to M36.
- Read the hole: Hole d1 min and max.
- Read the OD: d2 max; check it fits under the head or in a counterbore.
- Read the section: b is the section width and s the thickness.
- Check free height: h min and max is the uncompressed height of form A.
- Order it: Designate as Spring washer DIN 128 A 10.
DIN 128 A curved spring washer dimensions (mm)
Columns: thread, hole d1 min and max, OD d2 max, section width b, thickness s, free height h min and max (form A).
- Thread | d1 min | d1 max | d2 max | b | s | h min | h max
- M2 | 2.1 | 2.4 | 4.4 | 0.9 | 0.5 | 0.7 | 0.9
- M2.5 | 2.6 | 2.9 | 5.1 | 1 | 0.6 | 0.9 | 1.1
- M3 | 3.1 | 3.4 | 6.2 | 1.3 | 0.7 | 1.1 | 1.3
- M3.5 | 3.6 | 3.9 | 6.7 | 1.3 | 0.7 | 1.1 | 1.3
- M4 | 4.1 | 4.4 | 7.6 | 1.5 | 0.8 | 1.2 | 1.4
- M5 | 5.1 | 5.4 | 9.2 | 1.8 | 1 | 1.5 | 1.7
- M6 | 6.1 | 6.5 | 11.8 | 2.5 | 1.3 | 2 | 2.2
- M7 | 7.1 | 7.5 | — | 2.5 | 1.3 | 2 | 2.2
- M8 | 8.1 | 8.5 | 14.8 | 3 | 1.6 | 2.45 | 2.75
- M10 | 10.2 | 10.7 | 18.1 | 3.5 | 1.8 | 2.85 | 3.15
- M12 | 12.2 | 12.7 | 21.1 | 4 | 2.1 | 3.35 | 3.65
- M14 | 14.2 | 14.7 | 24.1 | 4.5 | 2.4 | 3.9 | 4.3
- M16 | 16.2 | 17 | 27.4 | 5 | 2.8 | 4.5 | 5.1
- M18 | 18.2 | 19 | 29.4 | 5 | 2.8 | 4.5 | 5.1
- M20 | 20.2 | 21.2 | 33.6 | 6 | 3.2 | 5.1 | 5.9
- M22 | 22.5 | 23.5 | 35.9 | 6 | 3.2 | 5.1 | 5.9
- M24 | 24.5 | 25.5 | 40 | 7 | 4 | 6.5 | 7.5
- M27 | 27.5 | 28.5 | 43 | 7 | 4 | 6.5 | 7.5
- M30 | 30.5 | 31.7 | 48.2 | 8 | 6 | 9.5 | 10.5
- M36 | 36.5 | 37.7 | 58.2 | 10 | 6 | 10.3 | 11.3
Worked example: M8 screw
An M8 DIN 128 A washer has an 8.1 to 8.5 mm hole, up to 14.8 mm OD, a 3 x 1.6 mm section and stands 2.45 to 2.75 mm before tightening.
Common problems
- Will not fit a counterbore: check d2 max.
- Washer splays under a large hole: add a flat washer.
- Mixed with DIN 127: DIN 128 is thinner; check s.
FAQ
What is DIN 128?
A split spring washer bent into a curve (form A, gewölbt) or a wave (form B, gewellt), unlike the helical DIN 127.
Is form B charted?
No. The form B tables found are partial (one lists only minimum hole, maximum OD, minimum height and thickness for M4 to M16), so only form A is charted.
Why is the M7 OD blank?
Sources disagree: 12.7 vs 12.8 mm.
DIN 128 vs DIN 127?
Same hole and OD at each size in the sources checked, but DIN 128 is thinner with a lower free height, e.g. M10 is 1.8 mm thick versus 2.2 mm for DIN 127 B.
What was skipped?
Form B, weights, radius r and the M7 OD.
Related guides and calculators
- Wave spring washers (DIN 137 B)
- Conical spring washers (DIN 6796)
- Spring lock washer dimensions (DIN 127 B)
- Serrated lock washer dimensions (DIN 6798)
- Tooth lock washer dimensions (DIN 6797)
- Flat washer size chart (SAE, USS, metric)
- All free machinist calculators
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