{
 "version": "2026-10-20",
 "license": "Dimension sheets: CC BY 4.0. Standard and published-size files: CC BY 4.0. Xem Studio's own designs (files_license = Xem Studio Design License): free to use and sell things from, not to redistribute as files — https://xemstudio.com/license/. Other publishers' files: their own license, linked beside them.",
 "slug": "split-pins-iso-1234",
 "name": "Split pins (cotter pins) ISO 1234 / DIN 94, 0.6–20: hole size, wire diameter d, a, b, c and the bolt and clevis-pin size each one serves",
 "kind": "standard",
 "category": "Hardware",
 "group": "Fasteners",
 "year": null,
 "question": "What size split pin (cotter pin) goes with a given clevis pin or bolt, and what are its d, a, b and c?",
 "tags": [
  "split pin",
  "cotter pin",
  "iso 1234",
  "din 94",
  "bs 1574",
  "split pin hole size",
  "cotter pin hole",
  "fastener",
  "retaining pin",
  "tool"
 ],
 "aliases": [
  "split pin sizes",
  "cotter pin dimensions",
  "cotter pin hole size for 10 mm clevis pin",
  "iso 1234 split pin",
  "din 94 cotter pin",
  "split pin size chart",
  "3.2 mm cotter pin dimensions",
  "cotter pin d a b c",
  "what size cotter pin for 8 mm bolt",
  "split pin length tolerance",
  "cotter pin hole diameter metric",
  "4 mm split pin eye length"
 ],
 "overall_mm": {
  "length": null,
  "width": null,
  "height": null
 },
 "official_cad": false,
 "xem_status": "not-scanned",
 "les": false,
 "free_files": 0,
 "url": "https://xemstudio.com/objects/split-pins-iso-1234/",
 "sheet_txt": "https://xemstudio.com/objects/split-pins-iso-1234/sheet.txt",
 "sheet": {
  "basis": "Westfield Fasteners' DIN 94 sheet (nominal 0.6 to 20 mm, d, a, b, c, plus the pin and bolt ranges per size), roymech's DIN 94 / ISO 1234 / BS 1574 table (agrees on every value it prints); numbers only",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "notes": [
   "Split pins (cotter pins) are sized by the hole they fit: the nominal size equals the hole diameter (Westfield: 'cotter pin holes match the nominal diameter'). Columns in mm: nominal size = hole, d (the wire section, max / min), a (the prong extension, max / min), b (eye length), c (eye outside, min / max), the length range roymech lists (l), the bolt diameter range the size serves (over x up to y) and the clevis-pin diameter range, and v min as printed in Westfield's application table (it does not define v). Westfield's sheet names DIN 94; roymech names DIN 94, ISO 1234 and BS 1574 together; the ISO 1234 text itself was not read, so the ISO match rests on roymech's statement and on identical d, a, b and c in the two tables.",
   "roymech does not list 0.6 and 16 mm and has no bolt ranges; where both print a value (0.8 to 13 mm) d max, a max, b and c agree. roymech's 8 mm row prints c max as '15,' (incomplete) and Westfield 15; the Westfield value is shown. Length tolerance on the shank (Westfield, DIN 94): 4 to 6 mm ±0.6, 8 to 10 ±0.75, 12 to 18 ±0.9, 20 to 28 ±1.0, 32 to 50 ±1.25, 56 to 80 ±1.5, 90 to 112 ±1.75, 125 to 180 ±2.0, 200 to 250 ±2.3, 280 ±2.6 mm.",
   "Use: a split pin goes through a cross hole in a clevis pin, bolt or shaft and its two halves are bent apart. Pick the size from the clevis pin's hole (ISO 2341 form B: d1 per size on clevis-pins-iso-2341). The ranges in the table are Westfield's application table; for clevis pins they match ISO 2341's hole for all 26 sizes (d 3 to 100). ISO 2341 also says to use the next larger pin and hole where alternating transverse forces act (iTeh's page for ISO 2341).",
   "No file: the pin is two half-round wires with a rolled eye; the cross-section and the eye form are not published as numbers in the sources read. Hairpin-style R-clips: r-clips-hairpin-cotters-din-11024. The existing page pins-clevises-and-joints lists a few model-work sizes."
  ],
  "table": {
   "columns": [
    "nominal size = hole (mm)",
    "d max / min",
    "a max / min",
    "b",
    "c min / max",
    "length range l (roymech)",
    "bolt d range, over to up to (mm)",
    "clevis pin d range, over to up to (mm)",
    "v min"
   ],
   "rows": [
    [
     "0.6",
     "0.5 / 0.4",
     "1.6 / 0.8",
     "2",
     "0.9 / 1",
     "—",
     "— to 2.5",
     "— to 2",
     "3"
    ],
    [
     "0.8",
     "0.7 / 0.6",
     "1.6 / 0.8",
     "2.4",
     "1.2 / 1.4",
     "6–12",
     "2.5 to 3.5",
     "2 to 3",
     "3"
    ],
    [
     "1",
     "0.9 / 0.8",
     "1.6 / 0.8",
     "3",
     "1.6 / 1.8",
     "6–12",
     "3.5 to 4.5",
     "3 to 4",
     "4"
    ],
    [
     "1.2",
     "1 / 0.9",
     "2.5 / 1.25",
     "3",
     "1.7 / 2",
     "6–40",
     "4.5 to 5.5",
     "4 to 5",
     "5"
    ],
    [
     "1.6",
     "1.4 / 1.3",
     "2.5 / 1.25",
     "3.2",
     "2.4 / 2.8",
     "6–40",
     "5.5 to 7",
     "5 to 6",
     "5"
    ],
    [
     "2",
     "1.8 / 1.7",
     "2.5 / 1.25",
     "4",
     "3.2 / 3.6",
     "6–50",
     "7 to 9",
     "6 to 8",
     "6"
    ],
    [
     "2.5",
     "2.3 / 2.1",
     "2.5 / 1.25",
     "5",
     "4 / 4.6",
     "8–50",
     "9 to 11",
     "8 to 9",
     "6"
    ],
    [
     "3.2",
     "2.9 / 2.7",
     "3.2 / 1.6",
     "6.4",
     "5.1 / 5.8",
     "8–63",
     "11 to 14",
     "9 to 12",
     "8"
    ],
    [
     "4",
     "3.7 / 3.5",
     "4 / 2",
     "8",
     "6.5 / 7.4",
     "16–100",
     "14 to 20",
     "12 to 17",
     "8"
    ],
    [
     "5",
     "4.6 / 4.4",
     "4 / 2",
     "10",
     "8 / 9.2",
     "20–100",
     "20 to 27",
     "17 to 23",
     "10"
    ],
    [
     "6.3",
     "5.9 / 5.7",
     "4 / 2",
     "12.6",
     "10.3 / 11.8",
     "25–125",
     "27 to 39",
     "23 to 29",
     "12"
    ],
    [
     "8",
     "7.5 / 7.3",
     "4 / 2",
     "16",
     "13.1 / 15",
     "40–140",
     "39 to 56",
     "29 to 44",
     "14"
    ],
    [
     "10",
     "9.5 / 9.3",
     "6.3 / 3.2",
     "20",
     "16.6 / 19",
     "50–140",
     "56 to 80",
     "44 to 69",
     "16"
    ],
    [
     "13",
     "12.4 / 12.1",
     "6.3 / 3.2",
     "26",
     "21.7 / 24.8",
     "71–140",
     "80 to 120",
     "69 to 110",
     "20"
    ],
    [
     "16",
     "15.4 / 15.1",
     "6.3 / 3.2",
     "26",
     "21.7 / 24.8",
     "—",
     "120 to 170",
     "110 to 160",
     "25"
    ],
    [
     "20",
     "19.3 / 19",
     "6.3 / 3.2",
     "40",
     "33.8 / 38.6",
     "—",
     "170 to —",
     "160 to —",
     "32"
    ]
   ]
  }
 },
 "sheet_text": "Split pins (cotter pins) ISO 1234 / DIN 94, 0.6–20: hole size, wire diameter d, a, b, c and the bolt and clevis-pin size each one serves — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/split-pins-iso-1234/  (sheet CC BY 4.0)\nBasis: Westfield Fasteners' DIN 94 sheet (nominal 0.6 to 20 mm, d, a, b, c, plus the pin and bolt ranges per size), roymech's DIN 94 / ISO 1234 / BS 1574 table (agrees on every value it prints); numbers only\nCatalog version: 2026-10-20\n\nSizes: see table below\n- Split pins (cotter pins) are sized by the hole they fit: the nominal size equals the hole diameter (Westfield: 'cotter pin holes match the nominal diameter'). Columns in mm: nominal size = hole, d (the wire section, max / min), a (the prong extension, max / min), b (eye length), c (eye outside, min / max), the length range roymech lists (l), the bolt diameter range the size serves (over x up to y) and the clevis-pin diameter range, and v min as printed in Westfield's application table (it does not define v). Westfield's sheet names DIN 94; roymech names DIN 94, ISO 1234 and BS 1574 together; the ISO 1234 text itself was not read, so the ISO match rests on roymech's statement and on identical d, a, b and c in the two tables.\n- roymech does not list 0.6 and 16 mm and has no bolt ranges; where both print a value (0.8 to 13 mm) d max, a max, b and c agree. roymech's 8 mm row prints c max as '15,' (incomplete) and Westfield 15; the Westfield value is shown. Length tolerance on the shank (Westfield, DIN 94): 4 to 6 mm ±0.6, 8 to 10 ±0.75, 12 to 18 ±0.9, 20 to 28 ±1.0, 32 to 50 ±1.25, 56 to 80 ±1.5, 90 to 112 ±1.75, 125 to 180 ±2.0, 200 to 250 ±2.3, 280 ±2.6 mm.\n- Use: a split pin goes through a cross hole in a clevis pin, bolt or shaft and its two halves are bent apart. Pick the size from the clevis pin's hole (ISO 2341 form B: d1 per size on clevis-pins-iso-2341). The ranges in the table are Westfield's application table; for clevis pins they match ISO 2341's hole for all 26 sizes (d 3 to 100). ISO 2341 also says to use the next larger pin and hole where alternating transverse forces act (iTeh's page for ISO 2341).\n- No file: the pin is two half-round wires with a rolled eye; the cross-section and the eye form are not published as numbers in the sources read. Hairpin-style R-clips: r-clips-hairpin-cotters-din-11024. The existing page pins-clevises-and-joints lists a few model-work sizes.\n\nnominal size = hole (mm)  d max / min  a max / min  b  c min / max  length range l (roymech)  bolt d range, over to up to (mm)  clevis pin d range, over to up to (mm)  v min\n0.6  0.5 / 0.4  1.6 / 0.8  2  0.9 / 1  —  — to 2.5  — to 2  3\n0.8  0.7 / 0.6  1.6 / 0.8  2.4  1.2 / 1.4  6–12  2.5 to 3.5  2 to 3  3\n1  0.9 / 0.8  1.6 / 0.8  3  1.6 / 1.8  6–12  3.5 to 4.5  3 to 4  4\n1.2  1 / 0.9  2.5 / 1.25  3  1.7 / 2  6–40  4.5 to 5.5  4 to 5  5\n1.6  1.4 / 1.3  2.5 / 1.25  3.2  2.4 / 2.8  6–40  5.5 to 7  5 to 6  5\n2  1.8 / 1.7  2.5 / 1.25  4  3.2 / 3.6  6–50  7 to 9  6 to 8  6\n2.5  2.3 / 2.1  2.5 / 1.25  5  4 / 4.6  8–50  9 to 11  8 to 9  6\n3.2  2.9 / 2.7  3.2 / 1.6  6.4  5.1 / 5.8  8–63  11 to 14  9 to 12  8\n4  3.7 / 3.5  4 / 2  8  6.5 / 7.4  16–100  14 to 20  12 to 17  8\n5  4.6 / 4.4  4 / 2  10  8 / 9.2  20–100  20 to 27  17 to 23  10\n6.3  5.9 / 5.7  4 / 2  12.6  10.3 / 11.8  25–125  27 to 39  23 to 29  12\n8  7.5 / 7.3  4 / 2  16  13.1 / 15  40–140  39 to 56  29 to 44  14\n10  9.5 / 9.3  6.3 / 3.2  20  16.6 / 19  50–140  56 to 80  44 to 69  16\n13  12.4 / 12.1  6.3 / 3.2  26  21.7 / 24.8  71–140  80 to 120  69 to 110  20\n16  15.4 / 15.1  6.3 / 3.2  26  21.7 / 24.8  —  120 to 170  110 to 160  25\n20  19.3 / 19  6.3 / 3.2  40  33.8 / 38.6  —  170 to —  160 to —  32\n\nFiles elsewhere (not hosted by Xem Studio; license as stated by the publisher):\n- Westfield Fasteners: DIN 94 split (cotter) pins, nominal 0.6 to 20: d max / min, a max / min, b, c min / max, length tolerances, bolt and clevis-pin ranges per size with v min — web — Reference page; numbers only — https://westfieldfasteners.co.uk/Standards/Pin-Cotter.pdf\n- roymech: Split cotter pins (DIN 94 / ISO 1234 / BS 1574): nominal size = hole, d, a, b, c and length range l — web — Reference page; numbers only — https://roymech.org/Useful_Tables/Circlips/Split_Cotter_Pins.html\n- ISO: ISO 1234:1976: Split pins, metric series (title as listed by ISO) (standard body catalogue page; the standard itself is paid) — web — Standard body catalogue page — https://www.iso.org/ics/21.060.50.html\n\nNo true-size file yet: the published figures do not fix the whole shape; a measured scan is planned.\nAPI: https://xemstudio.com/api/geometry?object=split-pins-iso-1234\n",
 "sources": [
  {
   "publisher": "Westfield Fasteners",
   "title": "DIN 94 split (cotter) pins, nominal 0.6 to 20: d max / min, a max / min, b, c min / max, length tolerances, bolt and clevis-pin ranges per size with v min",
   "url": "https://westfieldfasteners.co.uk/Standards/Pin-Cotter.pdf",
   "formats": [
    "web"
   ],
   "license": "Reference page; numbers only",
   "license_verified": true,
   "hosted": false
  },
  {
   "publisher": "roymech",
   "title": "Split cotter pins (DIN 94 / ISO 1234 / BS 1574): nominal size = hole, d, a, b, c and length range l",
   "url": "https://roymech.org/Useful_Tables/Circlips/Split_Cotter_Pins.html",
   "formats": [
    "web"
   ],
   "license": "Reference page; numbers only",
   "license_verified": true,
   "hosted": false
  },
  {
   "publisher": "ISO",
   "title": "ISO 1234:1976: Split pins, metric series (title as listed by ISO) (standard body catalogue page; the standard itself is paid)",
   "url": "https://www.iso.org/ics/21.060.50.html",
   "formats": [
    "web"
   ],
   "license": "Standard body catalogue page",
   "license_verified": true,
   "hosted": false
  }
 ],
 "xem": {
  "status": "not-scanned",
  "sheet_free": true,
  "mesh_price_usd": null,
  "step_price_usd": null,
  "tolerance_mm": null
 },
 "related": [
  "clevis-pins-iso-2341",
  "r-clips-hairpin-cotters-din-11024",
  "clevis-pins",
  "spring-pins-iso-8752-8750-asme-b18-8-2",
  "e-clips-din-6799",
  "retaining-rings-din-471-external"
 ],
 "fits": [],
 "dimensions": "exact (nominal, no tolerance added)",
 "dimension_rule": "All geometry on Xem Studio is exact (nominal, true size) with no tolerance added. Where a part meets another part, the object lists its mating features (feature, exact size, what it mates with, fit class: press, slide, run, socket, clamp or designed). Apply your process's allowance to those features only; 'designed' gaps are part of the design and stay as drawn. Typical accuracy by process and ISO 286 fits: https://xemstudio.com/tolerances/",
 "mating": [
  {
   "feature": "nominal size = hole",
   "exact": "0.6, 0.8, 1, 1.2, 1.6, 2, 2.5, 3.2, 4, 5, 6.3, 8, 10, 13, 16, 20 mm; d max 0.5 to 19.3 mm",
   "mates": "cross hole of that diameter in a clevis pin (ISO 2341 B d1) or bolt in the range of the table (Westfield)",
   "fit": "slide",
   "files": "all"
  },
  {
   "feature": "clevis pin range served",
   "exact": "2 mm split pin: clevis pins over 6 up to 8 mm; 3.2: over 9 up to 12; 5: over 17 up to 23; 8: over 29 up to 44; 13: over 69 up to 110 mm",
   "mates": "ISO 2341 clevis pin of that d on clevis-pins-iso-2341 (the table matches d1 for all 26 sizes)",
   "fit": "designed",
   "files": "all"
  }
 ],
 "fit_classes": {
  "press": "stays put: pin, tube, bearing or magnet held by interference. ISO 286 equivalent: H7/p6 (locational interference) or tighter.",
  "slide": "assembles by hand and is held by a grub, pinch or clamp: shaft in a hub, rod in a socket, spigot in a bore. ISO 286 equivalent: H7/g6 or H7/h6.",
  "run": "turns or slides in use: pin in a link, rod through a guide. ISO 286 equivalent: H8/f7 (close running).",
  "socket": "large sliding fit: syringe barrel, sleeve, bobbin in a bore. ISO 286 equivalent: H9/d9 (free running) or looser.",
  "clamp": "split part that closes on the mating part with screws: make it at size.",
  "designed": "a gap that is part of the design (piston fit option, displacer gap, air gap): do not change."
 },
 "faq": [
  {
   "q": "What split pin for an 8 mm clevis pin?",
   "a": "A 2 mm split pin: Westfield's application table puts clevis pins of 6 to 8 mm in the 2 mm size (hole Ø2); ISO 2341's hole for d 8 is 2 mm."
  },
  {
   "q": "Is the split pin size the pin diameter or the hole?",
   "a": "The hole: nominal size equals the hole diameter, and the wire diameter d is a little smaller (for 3.2 mm, d is 2.9 / 2.7 mm)."
  },
  {
   "q": "What is the eye length of a 4 mm split pin?",
   "a": "b is 8 mm, with the eye outside c 6.5 to 7.4 mm (Westfield and roymech)."
  }
 ],
 "files_license": null,
 "offers": [],
 "markdown": "https://xemstudio.com/objects/split-pins-iso-1234/index.md"
}