# Spring lock washers, DIN 127 B (split washers, rectangular section): M2–M100 bore, outside diameter, width, thickness, free height

> What are the dimensions of a DIN 127 B spring washer, and what is the outside diameter of an M8 split lock washer?

- Category: Hardware › Fasteners
- Kind: Standard part
- Basis: Westfield Fasteners' DIN 127 table (type B, 2 to 100 mm), cross-checked on 15 sizes against McMaster-Carr's DIN 127B lock washer listing (ID, OD, thickness range); numbers only
- Page: https://xemstudio.com/objects/spring-lock-washers-din-127-b/ · JSON: https://xemstudio.com/api/geometry?object=spring-lock-washers-din-127-b · Plain text: https://xemstudio.com/objects/spring-lock-washers-din-127-b/sheet.txt
- License: dimension sheet CC BY 4.0 (Xem Studio); files CC BY 4.0 or their publisher's license
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**Exact dimensions.** True size, with no tolerance added.

## Notes

- DIN 127 B is the helical spring (split) lock washer with square ends and rectangular section. Columns (mm): d1 bore min and max; d2 outside max; b width of section; s thickness; h free height of type B, min and max; r as printed. Rows b and s are 19 values per table after the label cell: the page's own markup puts a dash in the label column (limit column), so the dash is not a value. McMaster-Carr's thickness ranges agree with s on all 15 sizes compared (e.g. M6 1.5 to 1.7 against s 1.6; M10 2.0 to 2.4 against s 2.2; M24 4.8 to 5.2 against s 5), and McMaster's ID / OD equal d1 max and d2 max for those sizes.
- The last column shows McMaster-Carr's ID / OD / thickness range for the sizes it lists (M2, M2.5, M3, M4, M5, M6, M8, M10, M12, M16, M20, M24, M30, M36, M48). McMaster prints no width b. McMaster lists a few alternatives by finish (M3.5 3.9 or 3.6 mm bore in zinc steel; M27 27.5 or 28.5 mm) as printed there; Westfield's d1 for M27 is 27.5 min / 28.5 max, which explains the second value.
- One printed anomaly dropped: Westfield's type B minimum free height for size 39 reads 2 (neighbours 12 and 14); it is shown as a typo and left out. Sizes above M24 are given by their nominal size only on the Westfield table (sizes 30 to 100 have no M prefix in the header).
- Westfield's notes: DIN 127 applies to assemblies up to property class 5.8, reverse coil is recommended for left-hand threads, and type A (with prongs) is not tabulated here. The washer free height h is the coil height before tightening; the flat-state geometry (coil pitch, cut angle) is not given as numbers in the sources read, so no model is drawn.
- McMaster-Carr sells DIN 127B lock washers with per-part STEP; its DIN 127B category is linked, not copied.

## Sizes

| size | d1 min | d1 max | d2 max | b | s | h type B min | h type B max | r | McMaster ID / OD / thickness |
|---|---|---|---|---|---|---|---|---|---|
| M2 | 2.1 | 2.4 | 4.4 | 0.9 | 0.5 | 1 | 1.2 | 0.1 | 2.4 / 4.4 / 0.4 to 0.6 |
| M2.2 | 2.3 | 2.6 | 4.8 | 1 | 0.6 | 1.2 | 1.4 | 0.1 | — |
| M2.5 | 2.6 | 2.9 | 5.1 | 1 | 0.6 | 1.2 | 1.4 | 0.1 | 2.9 / 5.1 / 0.5 to 0.7 |
| M3 | 3.1 | 3.4 | 6.2 | 1.3 | 0.8 | 1.6 | 1.9 | 0.2 | 3.4 / 6.2 / 0.7 to 0.9 |
| M3.5 | 3.6 | 3.9 | 6.7 | 1.3 | 0.8 | 1.6 | 1.9 | 0.2 | — |
| M4 | 4.1 | 4.4 | 7.6 | 1.5 | 0.9 | 1.8 | 2.1 | 0.2 | 4.4 / 7.6 / 0.8 to 1.0 |
| M5 | 5.1 | 5.4 | 9.2 | 1.8 | 1.2 | 2.4 | 2.8 | 0.2 | 5.4 / 9.2 / 1.1 to 1.3 |
| M6 | 6.1 | 6.5 | 11.8 | 2.5 | 1.6 | 3.2 | 3.8 | 0.3 | 6.5 / 11.8 / 1.5 to 1.7 |
| M7 | 7.1 | 7.5 | 12.8 | 2.5 | 1.6 | 3.2 | 3.8 | 0.3 | — |
| M8 | 8.1 | 8.5 | 14.8 | 3 | 2 | 4 | 4.7 | 0.5 | 8.5 / 14.8 / 1.9 to 2.1 |
| M10 | 10.2 | 10.7 | 18.1 | 3.5 | 2.2 | 4.4 | 5.2 | 0.5 | 10.7 / 18.1 / 2.0 to 2.4 |
| M12 | 12.2 | 12.7 | 21.1 | 4 | 2.5 | 5 | 5.9 | 1 | 12.7 / 21.1 / 2.3 to 2.7 |
| M14 | 14.2 | 14.7 | 24.1 | 4.5 | 3 | 6 | 7.1 | 1 | — |
| M16 | 16.2 | 17 | 27.4 | 5 | 3.5 | 7 | 8.3 | 1 | 17.0 / 27.4 / 3.3 to 3.7 |
| M18 | 18.2 | 19 | 29.4 | 5 | 3.5 | 7 | 8.3 | 1 | — |
| M20 | 20.2 | 21.2 | 33.6 | 6 | 4 | 8 | 9.4 | 1 | 21.2 / 33.6 / 3.8 to 4.2 |
| M22 | 22.5 | 23.5 | 35.9 | 6 | 4 | 8 | 9.4 | 1 | — |
| M24 | 24.5 | 25.5 | 40 | 7 | 5 | 10 | 11.8 | 1.6 | 25.5 / 40.0 / 4.8 to 5.2 |
| M27 | 27.5 | 28.5 | 43 | 7 | 5 | 10 | 11.8 | 1.6 | — |
| M30 | 30.5 | 31.7 | 48.2 | 8 | 6 | 12 | 14.2 | 1.6 | 31.7 / 48.2 / 5.8 to 6.2 |
| M36 | 36.5 | 37.7 | 58.2 | 10 | 6 | 12 | 14.2 | 1.6 | 37.7 / 58.2 / 5.8 to 6.2 |
| M39 | 39.5 | 40.7 | 61.2 | 10 | 6 | — (printed 2; typo) | 14.2 | 1.6 | — |
| 42 | 42.5 | 43.7 | 68.2 | 12 | 7 | 14 | 16.5 | 2 | — |
| 45 | 45.5 | 46.7 | 71.2 | 12 | 7 | 14 | 16.5 | 2 | — |
| 48 | 49 | 50.5 | 75 | 12 | 7 | 14 | 16.5 | 2 | 50.5 / 75.0 / 6.8 to 7.2 |
| 52 | 53 | 54.5 | 83 | 14 | 8 | 16 | 18.9 | 2 | — |
| 56 | 57 | 58.5 | 87 | 14 | 8 | 16 | 18.9 | 2 | — |
| 60 | 61 | 62.5 | 91 | 14 | 8 | 16 | 18.9 | 2 | — |
| 64 | 65 | 66.5 | 95 | 14 | 8 | 16 | 18.9 | 2 | — |
| 68 | 69 | 70.5 | 99 | 14 | 8 | 16 | 18.9 | 2 | — |
| 72 | 73 | 74.5 | 103 | 14 | 8 | 16 | 18.9 | 2 | — |
| 80 | 81 | 82.5 | 111 | 14 | 8 | 16 | 18.9 | 2 | — |
| 90 | 91 | 92.5 | 121 | 14 | 8 | 16 | 18.9 | 2 | — |
| 100 | 101 | 102.5 | 131 | 14 | 8 | 16 | 18.9 | 2 | — |

## Where the files are

- Westfield Fasteners: [Helical spring washers, DIN 127 B rectangular section: d1 min / max, d2 max, b, s, h (type B), r, 2 to 100 mm](https://www.westfieldfasteners.co.uk/Standards/Washer-SprgRec-M.html) — web — Publisher's page; dimensions are facts
- McMaster-Carr: [DIN 127 B split lock washers (free STEP/IGES per part, for your own design use; no redistribution)](https://www.mcmaster.com/din-127b-lock-washers) — STEP, IGES, PDF — McMaster-Carr site terms: personal design use, no redistribution (verify at link)

## Questions

**What are the dimensions of an M8 DIN 127 B spring washer?**

Bore 8.1 to 8.5 mm, outside diameter 14.8 mm max, width b 3, thickness s 2, free height 4 to 4.7 mm (Westfield); McMaster lists 8.5 ID, 14.8 OD, thickness 1.9 to 2.1.

**What is the outside diameter of an M10 split lock washer?**

18.1 mm max (DIN 127 B, Westfield and McMaster agree); bore 10.2 to 10.7 mm, s 2.2.

## Fits with

- [Flat washers, M2–M8 (ISO 7089)](https://xemstudio.com/objects/flat-washers-metric/)
- [Flat washers, M10 to M24 (ISO 7089 / DIN 125-A)](https://xemstudio.com/objects/flat-washers-metric-m10-m24/)
- [Serrated (tooth) lock washers, DIN 6798 forms A, J, V: M1.6–M30 bore, outside diameter, thickness, number of teeth](https://xemstudio.com/objects/serrated-lock-washers-din-6798/)
- [Large (fender) washers, DIN 9021 / ISO 7093: M2.5–M36 bore, outside diameter, thickness + nylon variant + 8 washer files](https://xemstudio.com/objects/large-washers-din-9021-iso-7093/)
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