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Spring Lock Washer Dimensions (DIN 127 Form B, M2 to M48)

Guide · Updated October 28, 2026

DIN 127 covers split spring lock washers; this chart is form B (square ends), M2 to M48. Hole, OD, section width b, thickness s and form B free height h agree across the fasteners.eu DIN 127 B table, the HBS Solutions DIN 127 datasheet and the Ferrobolt DIN 127 B chart; the GM Singapore sheet matches the small sizes. Skipped: form A heights, weights, two conflicting cells, and DIN 128 (a different curved washer). Check your supplier for critical work.

Step by step

1. Pick the size: Choose by thread, M2 to M48.
2. Read the hole: Hole d1 min and max.
3. Read the OD: d2 max is the largest the washer can be; check it fits under the head or in a counterbore.
4. Read the section: b is the section width and s the thickness, both with small plus or minus tolerances.
5. Check free height: h min and max is the uncompressed height of form B; add s, not h, to the stack once flat.
6. Order it: Designate as Spring lock washer DIN 127 B 10.

DIN 127 B spring lock 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 B).

• Thread | d1 min | d1 max | d2 max | b | s | h min | h max
• M2 | 2.1 | 2.4 | 4.4 | 0.9 | 0.5 | 1 | 1.2
• M2.5 | 2.6 | 2.9 | 5.1 | 1 | 0.6 | 1.2 | 1.4
• M3 | 3.1 | 3.4 | 6.2 | 1.3 | 0.8 | 1.6 | 1.9
• M3.5 | 3.6 | 3.9 | 6.7 | 1.3 | 0.8 | 1.6 | 1.9
• M4 | 4.1 | 4.4 | 7.6 | 1.5 | 0.9 | 1.8 | 2.1
• M5 | 5.1 | 5.4 | 9.2 | 1.8 | 1.2 | 2.4 | 2.8
• M6 | — | 6.5 | 11.8 | 2.5 | 1.6 | 3.2 | 3.8
• M7 | 7.1 | 7.5 | 12.8 | 2.5 | 1.6 | 3.2 | 3.8
• M8 | 8.1 | 8.5 | 14.8 | 3 | 2 | 4 | 4.7
• M10 | 10.2 | 10.7 | 18.1 | 3.5 | 2.2 | 4.4 | 5.2
• M12 | 12.2 | 12.7 | 21.1 | 4 | 2.5 | 5 | 5.9
• M14 | 14.2 | 14.7 | 24.1 | 4.5 | 3 | 6 | 7.1
• M16 | 16.2 | 17 | 27.4 | 5 | 3.5 | 7 | 8.3
• M18 | 18.2 | 19 | 29.4 | 5 | 3.5 | 7 | 8.3
• M20 | 20.2 | 21.2 | 33.6 | 6 | 4 | 8 | 9.4
• M22 | 22.5 | 23.5 | 35.9 | 6 | 4 | 8 | 9.4
• M24 | 24.5 | 25.5 | 40 | 7 | 5 | 10 | 11.8
• M27 | 27.5 | 28.5 | 43 | 7 | 5 | 10 | 11.8
• M30 | 30.5 | 31.7 | 48.2 | 8 | 6 | 12 | 14.2
• M36 | 36.5 | 37.7 | 58.2 | 10 | 6 | 12 | 14.2
• M39 | 39.5 | 40.7 | 61.2 | 10 | 6 | 12 | 14.2
• M42 | 42.5 | 43.7 | — | 12 | 7 | 14 | 16.5
• M45 | 45.5 | 46.7 | 71.2 | 12 | 7 | 14 | 16.5
• M48 | 49 | 50.6 | 75 | 12 | 7 | 14 | 16.5

Worked example: M10 bolt

An M10 DIN 127 B washer has a 10.2 to 10.7 mm hole, up to 18.1 mm OD, a 3.5 x 2.2 mm section and stands 4.4 to 5.2 mm tall before tightening.

Common problems

• Washer splays under a large hole: put a flat washer under it.
• Will not fit a counterbore: check d2 max.
• Cracked washer: hydrogen embrittlement from plating on hardened steel.

FAQ

What is DIN 127?

A split (helical) spring lock washer. Form A has bent-up tang ends and form B has square (plain) ends. Form B is the common one and is what this chart covers.

Why not form A?

Form A free height is listed by only one source, so it is not charted.

Why are two cells blank?

Sources conflict: M6 hole min (6.1 vs 6.4 mm) and M42 OD (66.2 vs 68.2 mm).

What about DIN 128?

DIN 128 is the curved or wavy spring washer, a different part. It is not covered here.

Do split lock washers stop loosening?

Under high preload they flatten and add little. For critical joints use proper preload or a tested locking method.

Related guides and calculators

• Thick washers (DIN 7349)
• Wave spring washers (DIN 137 B)
• Conical spring washers (DIN 6796)
• Curved spring washers (DIN 128 A)
• Chamfered washers (DIN 125 B / ISO 7090)
• Tooth lock washers (DIN 6797)
• Serrated lock washer dimensions (DIN 6798)
• Large OD washer dimensions (DIN 9021)
• Flat washer size chart (SAE, USS, metric)
• Heavy-duty washer dimensions (DIN 7989)
• All free machinist calculators

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