# Slotted and castle nuts, DIN 935-1, M4–M36: across flats, height, slot width, collar, cotter pin size + envelope models

> What are the dimensions of a DIN 935 castle nut or slotted nut, and what cotter pin does it take?

- Category: Hardware › Fasteners
- Kind: Standard part
- Basis: fasten.it's DIN 935-1 table (editions 2013 and 2000) cross-checked against Ferrofast, Aspen Fasteners and ITA Fasteners, cotter pin sizes from Aspen and ITA with McMaster-Carr's metric slotted-nut table as a check; six envelope models as files
- Page: https://xemstudio.com/objects/slotted-castle-nuts-din-935/ · JSON: https://xemstudio.com/api/geometry?object=slotted-castle-nuts-din-935 · Plain text: https://xemstudio.com/objects/slotted-castle-nuts-din-935/sheet.txt
- License: dimension sheet CC BY 4.0 (Xem Studio); files CC BY 4.0 or their publisher's license
- Use in every chat: add https://xemstudio.com/mcp as a connector (https://xemstudio.com/use-with-ai/)

## Overall (mm)

| length | width | height |
|---|---|---|
| 11.5 | 10.0 | 7.5 |

**Exact dimensions.** Every file is drawn at true size with no tolerance added. The holes and pins that meet another part are listed below under Mating features, with the fit each joint needs; open those by your process's clearance before making the part.

## Notes

- DIN 935-1 covers hexagon slotted nuts (M4 to M10: the slots are cut in a plain hex) and castle nuts (M12 and up have a round collar above the hex) in metric coarse and fine thread, product grade A up to M16 and B above. Rows are M4 to M36 in mm: pitch P, width across flats s, width across corners e (min), height m, w (the page's letter; read here as the height of the unslotted part, which is how the inch tables use the same idea), slot width n (min – max), collar diameter ds (max, M12 and up). The fasten.it page does not define its letters. Ferrofast's table (M4 to M100) agrees with fasten.it on s, m, w, e and n min for every size shown here.
- Older and newer values: Ferrofast prints s 17 / 19 / 22 and e 18.90 / 21.10 / 24.49 in brackets for M10 / M12 / M14, and Aspen's older table has s 17 for M10, 19 for M12 and a collar D1 of 17 for M12; fasten.it's current values are s 16 / 18 / 21 for those sizes. The fasten.it page prints two editions (08-2013 and 10-2000); the rows shown are the ones both print for these sizes except that the page notes M22's collar differs between editions (32 against 30), and M22 is not tabulated here. Use the edition your drawing cites.
- Cotter pins: the 'cotter pin' column is the DIN 94 size (diameter × length, mm) printed by Aspen Fasteners and, for M4, M5, M6, M8 and M20, by ITA Fasteners (ITA prints 1.2 × 12 for M5 where Aspen's text is cut off at '1.2x2'; ITA's M20 '4.36' is read as 4 × 36). McMaster-Carr's metric slotted-nut table gives the cotter pin diameter for the nut: 1.6 (M6), 2 (M8), 2.5 (M10), 3.2 (M12, M14), 4 (M16, M20), 5 (M24), 6.3 (M30, M36), matching Aspen where both have a size. A slot depth column is shown as m − w (computed); the standards pages do not print a slot depth.
- ITA Fasteners names ISO 7035 as an equivalent norm of DIN 935; the ISO text was not read, so no ISO value is tabulated. DIN 937 (thin castle nut) is not on this page.
- Files are Xem-drawn envelopes: a hexagon at the published width across flats and height m with six slots (three straight cuts 60° apart) of width n max to depth m − w; for M12 and up the part above the hex is a plain cylinder of diameter ds max, so the six slots cut through the collar. The bore is a plain cylinder at the thread major diameter (the real thread is smaller); no chamfers, washer face or countersink. M6, M8, M10 are hex slotted nuts; M12, M16, M20 are castle nuts.
- McMaster-Carr sells slotted and castle nuts with per-part STEP; the metric slotted-nut and castellated-nut categories are linked, not copied. Inch versions: slotted-castle-nuts-inch-asme-b18-2-2.

## Mating features (exact size; open press / slide / run / socket by your process clearance, leave designed and clamp as drawn)

| feature | exact | mates with | fit | files |
|---|---|---|---|---|
| bore (thread as plain cylinder) | thread major diameter: M6 Ø6, M8 Ø8, M10 Ø10, M12 Ø12, M16 Ø16, M20 Ø20 mm | bolt or stud of the same thread (plain cylinder at the major Ø) | designed | din-935-* |
| six slots | width n max: M6 2.25, M8 2.75, M10 3.05, M12 3.8, M16 4.8, M20 4.8 mm; depth m − w: 2.5, 3, 4, 5, 6, 6 mm | cotter pin through the drilled bolt (DIN 94 per Aspen / ITA): 1.6 × 14, 2 × 16, 2.5 × 20, 3.2 × 22, 4 × 28, 4 × 36 mm | slide | din-935-* |
| hex body | s across flats: M6 10, M8 13, M10 16, M12 18, M16 24, M20 30 mm | hex pocket or wrench that captures the nut: width = s | slide | din-935-* |

## Sizes

| size | P (mm) | s (AF) | e min | m (height) | w (unslotted height, as read) | n slot width (min – max) | ds max (collar, M12+) | cotter pin d × l (DIN 94, mm) | slot depth m − w (computed) |
|---|---|---|---|---|---|---|---|---|---|
| M4 | 0.7 | 7 | 7.66 | 5 | 3.2 | 1.2 – 1.45 | — | 1 × 10 | 1.8 |
| M5 | 0.8 | 8 | 8.79 | 6 | 4 | 1.4 – 1.65 | — | 1.2 × 12 | 2 |
| M6 | 1 | 10 | 11.05 | 7.5 | 5 | 2 – 2.25 | — | 1.6 × 14 | 2.5 |
| M8 | 1.25 | 13 | 14.38 | 9.5 | 6.5 | 2.5 – 2.75 | — | 2 × 16 | 3 |
| M10 | 1.5 | 16 | 17.77 | 12 | 8 | 2.8 – 3.05 | — | 2.5 × 20 | 4 |
| M12 | 1.75 | 18 | 20.03 | 15 | 10 | 3.5 – 3.8 | 16 | 3.2 × 22 | 5 |
| M14 | 2 | 21 | 23.35 | 16 | 11 | 3.5 – 3.8 | 18 | — (McMaster hole 3.2) | 5 |
| M16 | 2 | 24 | 26.75 | 19 | 13 | 4.5 – 4.8 | 22 | 4 × 28 | 6 |
| M20 | 2.5 | 30 | 32.95 | 22 | 16 | 4.5 – 4.8 | 28 | 4 × 36 | 6 |
| M24 | 3 | 36 | 39.55 | 27 | 19 | 5.5 – 5.8 | 34 | 5 × 40 | 8 |
| M30 | 3.5 | 46 | 50.85 | 33 | 24 | 7 – 7.36 | 42 | 6.3 × 50 | 9 |
| M36 | 4 | 55 | 60.79 | 38 | 29 | 7 – 7.36 | 50 | 6.3 × 63 | 9 |

## Where the files are

- fasten.it: [DIN 935-1 Hexagon slotted and castle nuts, metric coarse and fine pitch thread, product grades A and B, M4 to M100 (editions 08-2013 and 10-2000): P, ds max, m max, w max, s, e min, n min / max](https://fasten.it/norms/norm/din_935_1) — web — Reference page (tables reproduced there by permission of DIN); numbers only. Column letters are not defined on the page
- Ferrofast: [DIN 935 table M4 to M100: d1, s, m max, w max, n min, e min (with the older s / e in brackets for M10, M12, M14, M22)](https://ferrofastco.ferrobend.com/resources/dimensional-standards/din/nuts/din-935) — web — Distributor reference; numbers only
- Aspen Fasteners: [Metric DIN 935 spec: D, D1, M, S, E, N, P and cotter pin (DIN 94) size per nut size, older table (S 17 / 19 for M10 / M12)](https://www.aspenfasteners.com/v/vspfiles/files/docs/Metric_DIN_935_spec.pdf) — web — Distributor data sheet; numbers only. Letters are not defined in the document
- ITA Fasteners: [Castle nuts: DIN 935 rows (P, da, de, dw, e, m, m', n, s, w, split pin DIN 94 size) M4 to M8 and M20; names ISO 7035 as an equivalent norm](https://itafasteners.com/products-nuts-castle.php) — web — Distributor reference; numbers only
- McMaster-Carr: [Metric slotted nuts (cotter pin diameter per size) (free STEP/IGES per part, for your own design use; no redistribution)](https://www.mcmaster.com/metric-slotted-nuts) — STEP, IGES, PDF — McMaster-Carr site terms: personal design use, no redistribution (verify at link)
- McMaster-Carr: [Castellated nuts (free STEP/IGES per part, for your own design use; no redistribution)](https://www.mcmaster.com/castellated-nuts) — STEP, IGES, PDF — McMaster-Carr site terms: personal design use, no redistribution (verify at link)

## Free STEP/STL (6 parts, CC BY 4.0, Xem Studio)

Index: https://xemstudio.com/files/hardware/slotted-castle-nuts-din-935/index.json

- din-935-m6-slotted-nut-envelope: [STEP](https://xemstudio.com/files/hardware/slotted-castle-nuts-din-935/din-935-m6-slotted-nut-envelope.step) · [STL](https://xemstudio.com/files/hardware/slotted-castle-nuts-din-935/din-935-m6-slotted-nut-envelope.stl) — DIN 935-1 M6 hexagon slotted nut: hex 10 mm across flats, height 7.5, unslotted height 5, six slots 2.25 mm wide (n max) and 2.5 mm deep, bore Ø6 (thread major diameter as a plain cylinder); no chamfers, no thread, no countersink
- din-935-m8-slotted-nut-envelope: [STEP](https://xemstudio.com/files/hardware/slotted-castle-nuts-din-935/din-935-m8-slotted-nut-envelope.step) · [STL](https://xemstudio.com/files/hardware/slotted-castle-nuts-din-935/din-935-m8-slotted-nut-envelope.stl) — DIN 935-1 M8 hexagon slotted nut: hex 13 mm across flats, height 9.5, unslotted height 6.5, six slots 2.75 mm wide (n max) and 3 mm deep, bore Ø8 (thread major diameter as a plain cylinder); no chamfers, no thread, no countersink
- din-935-m10-slotted-nut-envelope: [STEP](https://xemstudio.com/files/hardware/slotted-castle-nuts-din-935/din-935-m10-slotted-nut-envelope.step) · [STL](https://xemstudio.com/files/hardware/slotted-castle-nuts-din-935/din-935-m10-slotted-nut-envelope.stl) — DIN 935-1 M10 hexagon slotted nut: hex 16 mm across flats, height 12, unslotted height 8, six slots 3.05 mm wide (n max) and 4 mm deep, bore Ø10 (thread major diameter as a plain cylinder); no chamfers, no thread, no countersink
- din-935-m12-castle-nut-envelope: [STEP](https://xemstudio.com/files/hardware/slotted-castle-nuts-din-935/din-935-m12-castle-nut-envelope.step) · [STL](https://xemstudio.com/files/hardware/slotted-castle-nuts-din-935/din-935-m12-castle-nut-envelope.stl) — DIN 935-1 M12 castle nut (collar Ø16): hex 18 mm across flats, height 15, unslotted height 10, six slots 3.8 mm wide (n max) and 5 mm deep, bore Ø12 (thread major diameter as a plain cylinder); no chamfers, no thread, no countersink
- din-935-m16-castle-nut-envelope: [STEP](https://xemstudio.com/files/hardware/slotted-castle-nuts-din-935/din-935-m16-castle-nut-envelope.step) · [STL](https://xemstudio.com/files/hardware/slotted-castle-nuts-din-935/din-935-m16-castle-nut-envelope.stl) — DIN 935-1 M16 castle nut (collar Ø22): hex 24 mm across flats, height 19, unslotted height 13, six slots 4.8 mm wide (n max) and 6 mm deep, bore Ø16 (thread major diameter as a plain cylinder); no chamfers, no thread, no countersink
- din-935-m20-castle-nut-envelope: [STEP](https://xemstudio.com/files/hardware/slotted-castle-nuts-din-935/din-935-m20-castle-nut-envelope.step) · [STL](https://xemstudio.com/files/hardware/slotted-castle-nuts-din-935/din-935-m20-castle-nut-envelope.stl) — DIN 935-1 M20 castle nut (collar Ø28): hex 30 mm across flats, height 22, unslotted height 16, six slots 4.8 mm wide (n max) and 6 mm deep, bore Ø20 (thread major diameter as a plain cylinder); no chamfers, no thread, no countersink

## Questions

**What cotter pin fits an M12 castle nut?**

3.2 mm diameter: Aspen Fasteners lists 3.2 × 22 (DIN 94) and McMaster-Carr lists 3.2 mm for M12 and M14.

**How wide is the slot in an M10 DIN 935 slotted nut?**

n is 2.8 mm min to 3.05 mm max in fasten.it's table; the nut is 16 mm across flats and 12 mm high, with an unslotted height w of 8 mm.

**Which M sizes have a round collar?**

M12 and up: fasten.it prints a collar diameter ds max of 16 (M12), 18 (M14), 22 (M16), 28 (M20), 34 (M24), 42 (M30), 50 (M36); M4 to M10 are slotted hex nuts with no collar value.

## Fits with

- [Slotted and castle nuts, inch (ASME B18.2.2): hex slotted 1/4 to 2 in, castle 1/4 to 1-1/4 in — across flats, height, slot width, cotter hole + envelope models](https://xemstudio.com/objects/slotted-castle-nuts-inch-asme-b18-2-2/)
- [Hex nuts, M2–M8 (ISO 4032)](https://xemstudio.com/objects/hex-nuts-metric/)
- [Hex nuts, M10 to M24 (ISO 4032 / DIN 934)](https://xemstudio.com/objects/hex-nuts-metric-m10-m24/)
- [Coupling nuts / long hex nuts: DIN 6334 M8–M36 (height 3 d) and inch rod coupling nuts 1/4 to 1 in — across flats, length + M8–M36 envelope models](https://xemstudio.com/objects/coupling-nuts-din-6334-and-inch/)
- [All-metal prevailing-torque lock nuts: DIN 980 V / M, ISO 7042 M5–M36 and inch Stover-type / top-lock nuts — across flats, height](https://xemstudio.com/objects/prevailing-torque-all-metal-nuts/)
- [Nyloc lock nuts, M2.5–M8 (DIN 985)](https://xemstudio.com/objects/nyloc-nuts-metric/)
- [R-clips, spring cotters and hairpin cotter pins: wire diameter, pin / shaft range, length (DIN 11024, McMaster hairpin sizes)](https://xemstudio.com/objects/r-clips-hairpin-cotters-din-11024/)
- [Clevis pins ISO 2341 B, Ø3 to Ø8](https://xemstudio.com/objects/clevis-pins/)
- [Threaded rod, metric M3 to M12 (DIN 976), 100 to 1000 mm](https://xemstudio.com/objects/threaded-rod-metric-din-976/)