{
 "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": "double-end-studs-inch-asme-b18-31-2",
 "name": "Double-end studs, inch (ASME B18.31.2): clamping-type and tap-end studs 1/4 to 4 in, thread length B, body diameter, UNC / UNF",
 "kind": "standard",
 "category": "Hardware",
 "group": "Fasteners",
 "year": null,
 "question": "How long is the thread on an ASME B18.31.2 stud (1/2-13, 3/4-10), and what is the body diameter?",
 "tags": [
  "stud",
  "double end stud",
  "stud bolt",
  "asme b18.31.2",
  "clamping stud",
  "tap end stud",
  "threaded stud",
  "unc",
  "unf",
  "fastener",
  "inch",
  "tool"
 ],
 "aliases": [
  "double end stud thread length",
  "1/2-13 stud thread length",
  "3/4-10 double end stud",
  "stud bolt 5/8 thread length",
  "asme b18.31.2 stud dimensions",
  "tap end stud 1.5d",
  "stud body diameter 1/2-13",
  "inch stud thread length chart",
  "double ended stud 3/8-16",
  "stud bolt screw in length 1d",
  "stud length tolerance inch",
  "1-1/4 stud b min"
 ],
 "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/double-end-studs-inch-asme-b18-31-2/",
 "sheet_txt": "https://xemstudio.com/objects/double-end-studs-inch-asme-b18-31-2/sheet.txt",
 "sheet": {
  "basis": "fasten.it's ASME B18.31.2 Tables 2 (clamping type) and 3 (tap-end, 1.5D engagement) cross-checked with Torqbolt's inch and mm tables (same B min values, plus body diameter DS and length tolerance); numbers only",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "notes": [
   "Inches (thread size also in mm). ASME B18.31.2 covers continuous-thread and double-end studs. Clamping-type double-end studs (equal thread at both ends, a nut on each end) and tap-end studs (a long thread to screw into a tapped hole, 1.5D engagement). Columns: threads per inch for the UNC and UNF series; Bm, the nominal thread length of the tap end (fasten.it Table 3, 1.5D engagement); B min, the minimum full-thread length at each end, for stud length L ≤ 10 in, 10 < L ≤ 16 in and L > 16 in (fasten.it and Torqbolt agree on every B min value; Torqbolt also prints them in mm, e.g. 1/4 in: 19.050, 25.400, 38.100); and the minimum body diameter DS (Torqbolt) for UNC and NC-5 HF threads, UNF threads, and 8UN threads (for 1-1/8 in and up).",
   "Where a table gives no value (a dash) the standard lists none: e.g. no UNF series above 1-1/2 in, and no 'L ≤ 10 in' value from 3 in thread size up. The sources do not give the body diameter for the smaller sizes in the 8UN column.",
   "The DIN equivalents (DIN 938 / 939, metric) are on studs-din-938-din-939. Length tolerance (Torqbolt, inches): ±0.04 for stud lengths 3/4 to 2-1/2 in, ±0.08 over 2-1/2 to 4, ±0.10 over 4 to 8, ±0.12 over 8 to 16 and ±0.18 over 16.",
   "No files: a double-end stud with a body only slightly smaller than the thread is a plain stepped cylinder, and a plain cylinder is not worth a model. Left out: the thread-end point and chamfer (not published as numbers in the pages read)."
  ],
  "table": {
   "columns": [
    "thread size (in)",
    "mm",
    "UNC (tpi)",
    "UNF (tpi)",
    "Bm tap end (in)",
    "B min, L ≤ 10 in",
    "B min, 10 < L ≤ 16 in",
    "B min, L > 16 in",
    "DS min body, UNC (in)",
    "DS min body, UNF (in)",
    "DS min body, 8UN (in)"
   ],
   "rows": [
    [
     "1/4",
     6.35,
     "20",
     "28",
     0.375,
     "0.75",
     "1",
     "1.5",
     ".241",
     ".243",
     "—"
    ],
    [
     "5/16",
     7.94,
     "18",
     "24",
     0.469,
     "0.875",
     "1.125",
     "1.625",
     ".303",
     ".304",
     "—"
    ],
    [
     "3/8",
     9.53,
     "16",
     "24",
     0.563,
     "1",
     "1.25",
     "1.75",
     ".364",
     ".367",
     "—"
    ],
    [
     "7/16",
     11.11,
     "14",
     "20",
     0.656,
     "1.125",
     "1.375",
     "1.875",
     ".426",
     ".428",
     "—"
    ],
    [
     "1/2",
     12.7,
     "13",
     "20",
     0.75,
     "1.25",
     "1.5",
     "2",
     ".488",
     ".491",
     "—"
    ],
    [
     "9/16",
     14.29,
     "12",
     "18",
     0.844,
     "1.375",
     "1.625",
     "2.125",
     ".550",
     ".552",
     "—"
    ],
    [
     "5/8",
     15.88,
     "11",
     "18",
     0.938,
     "1.5",
     "1.75",
     "2.25",
     ".611",
     ".615",
     "—"
    ],
    [
     "3/4",
     19.05,
     "10",
     "16",
     1.125,
     "1.75",
     "2",
     "2.5",
     ".735",
     ".739",
     "—"
    ],
    [
     "7/8",
     22.23,
     "9",
     "14",
     1.313,
     "2",
     "2.25",
     "2.75",
     ".859",
     ".863",
     "—"
    ],
    [
     "1",
     25.4,
     "8",
     "12",
     1.5,
     "2.25",
     "2.5",
     "3",
     ".983",
     ".987",
     "—"
    ],
    [
     "1-1/8",
     28.58,
     "7",
     "12",
     1.688,
     "2.5",
     "2.75",
     "3.25",
     "1.106",
     "1.112",
     "1.108"
    ],
    [
     "1-1/4",
     31.75,
     "7",
     "12",
     1.875,
     "2.75",
     "3",
     "3.5",
     "1.231",
     "1.237",
     "1.233"
    ],
    [
     "1-3/8",
     34.93,
     "6",
     "12",
     2.063,
     "3",
     "3.25",
     "3.75",
     "1.354",
     "1.362",
     "1.358"
    ],
    [
     "1-1/2",
     38.1,
     "6",
     "12",
     2.25,
     "3.25",
     "3.5",
     "4",
     "1.479",
     "1.487",
     "1.483"
    ],
    [
     "1-5/8",
     41.28,
     "—",
     "—",
     2.438,
     "3.5",
     "3.75",
     "4.25",
     "—",
     "—",
     "1.608"
    ],
    [
     "1-3/4",
     44.45,
     "5",
     "—",
     2.625,
     "3.75",
     "4",
     "4.5",
     "1.727",
     "—",
     "1.733"
    ],
    [
     "1-7/8",
     47.63,
     "—",
     "—",
     2.813,
     "4",
     "4.25",
     "4.75",
     "—",
     "—",
     "1.858"
    ],
    [
     "2",
     50.8,
     "4.5",
     "—",
     3,
     "4.25",
     "4.5",
     "5",
     "1.975",
     "—",
     "1.983"
    ],
    [
     "2-1/4",
     57.15,
     "4.5",
     "—",
     3.375,
     "4.75",
     "5",
     "5.5",
     "2.225",
     "—",
     "2.233"
    ],
    [
     "2-1/2",
     63.5,
     "4",
     "—",
     3.75,
     "5.25",
     "5.5",
     "6",
     "2.473",
     "—",
     "2.483"
    ],
    [
     "2-3/4",
     69.85,
     "4",
     "—",
     4.125,
     "5.75",
     "6",
     "6.5",
     "2.723",
     "—",
     "2.733"
    ],
    [
     "3",
     76.2,
     "4",
     "—",
     4.5,
     "—",
     "6.5",
     "7",
     "2.973",
     "—",
     "2.982"
    ],
    [
     "3-1/4",
     82.55,
     "4",
     "—",
     4.875,
     "—",
     "7",
     "7.5",
     "3.223",
     "—",
     "3.232"
    ],
    [
     "3-1/2",
     88.9,
     "4",
     "—",
     5.25,
     "—",
     "7.5",
     "8",
     "3.473",
     "—",
     "3.482"
    ],
    [
     "3-3/4",
     95.25,
     "4",
     "—",
     5.625,
     "—",
     "8",
     "8.5",
     "3.723",
     "—",
     "3.732"
    ],
    [
     "4",
     101.6,
     "4",
     "—",
     6,
     "—",
     "8.5",
     "9",
     "3.973",
     "—",
     "3.982"
    ],
    [
     "length tolerance (inches), Torqbolt",
     "—",
     "—",
     "—",
     "—",
     "±0.04 for L 3/4 to 2-1/2; ±0.08 over 2-1/2 to 4",
     "±0.10 over 4 to 8; ±0.12 over 8 to 16",
     "±0.18 over 16",
     "—",
     "—",
     "—"
    ]
   ]
  }
 },
 "sheet_text": "Double-end studs, inch (ASME B18.31.2): clamping-type and tap-end studs 1/4 to 4 in, thread length B, body diameter, UNC / UNF — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/double-end-studs-inch-asme-b18-31-2/  (sheet CC BY 4.0)\nBasis: fasten.it's ASME B18.31.2 Tables 2 (clamping type) and 3 (tap-end, 1.5D engagement) cross-checked with Torqbolt's inch and mm tables (same B min values, plus body diameter DS and length tolerance); numbers only\nCatalog version: 2026-10-20\n\nSizes: see table below\n- Inches (thread size also in mm). ASME B18.31.2 covers continuous-thread and double-end studs. Clamping-type double-end studs (equal thread at both ends, a nut on each end) and tap-end studs (a long thread to screw into a tapped hole, 1.5D engagement). Columns: threads per inch for the UNC and UNF series; Bm, the nominal thread length of the tap end (fasten.it Table 3, 1.5D engagement); B min, the minimum full-thread length at each end, for stud length L ≤ 10 in, 10 < L ≤ 16 in and L > 16 in (fasten.it and Torqbolt agree on every B min value; Torqbolt also prints them in mm, e.g. 1/4 in: 19.050, 25.400, 38.100); and the minimum body diameter DS (Torqbolt) for UNC and NC-5 HF threads, UNF threads, and 8UN threads (for 1-1/8 in and up).\n- Where a table gives no value (a dash) the standard lists none: e.g. no UNF series above 1-1/2 in, and no 'L ≤ 10 in' value from 3 in thread size up. The sources do not give the body diameter for the smaller sizes in the 8UN column.\n- The DIN equivalents (DIN 938 / 939, metric) are on studs-din-938-din-939. Length tolerance (Torqbolt, inches): ±0.04 for stud lengths 3/4 to 2-1/2 in, ±0.08 over 2-1/2 to 4, ±0.10 over 4 to 8, ±0.12 over 8 to 16 and ±0.18 over 16.\n- No files: a double-end stud with a body only slightly smaller than the thread is a plain stepped cylinder, and a plain cylinder is not worth a model. Left out: the thread-end point and chamfer (not published as numbers in the pages read).\n\nthread size (in)  mm  UNC (tpi)  UNF (tpi)  Bm tap end (in)  B min, L ≤ 10 in  B min, 10 < L ≤ 16 in  B min, L > 16 in  DS min body, UNC (in)  DS min body, UNF (in)  DS min body, 8UN (in)\n1/4  6.35  20  28  0.375  0.75  1  1.5  .241  .243  —\n5/16  7.94  18  24  0.469  0.875  1.125  1.625  .303  .304  —\n3/8  9.53  16  24  0.563  1  1.25  1.75  .364  .367  —\n7/16  11.11  14  20  0.656  1.125  1.375  1.875  .426  .428  —\n1/2  12.7  13  20  0.75  1.25  1.5  2  .488  .491  —\n9/16  14.29  12  18  0.844  1.375  1.625  2.125  .550  .552  —\n5/8  15.88  11  18  0.938  1.5  1.75  2.25  .611  .615  —\n3/4  19.05  10  16  1.125  1.75  2  2.5  .735  .739  —\n7/8  22.23  9  14  1.313  2  2.25  2.75  .859  .863  —\n1  25.4  8  12  1.5  2.25  2.5  3  .983  .987  —\n1-1/8  28.58  7  12  1.688  2.5  2.75  3.25  1.106  1.112  1.108\n1-1/4  31.75  7  12  1.875  2.75  3  3.5  1.231  1.237  1.233\n1-3/8  34.93  6  12  2.063  3  3.25  3.75  1.354  1.362  1.358\n1-1/2  38.1  6  12  2.25  3.25  3.5  4  1.479  1.487  1.483\n1-5/8  41.28  —  —  2.438  3.5  3.75  4.25  —  —  1.608\n1-3/4  44.45  5  —  2.625  3.75  4  4.5  1.727  —  1.733\n1-7/8  47.63  —  —  2.813  4  4.25  4.75  —  —  1.858\n2  50.8  4.5  —  3  4.25  4.5  5  1.975  —  1.983\n2-1/4  57.15  4.5  —  3.375  4.75  5  5.5  2.225  —  2.233\n2-1/2  63.5  4  —  3.75  5.25  5.5  6  2.473  —  2.483\n2-3/4  69.85  4  —  4.125  5.75  6  6.5  2.723  —  2.733\n3  76.2  4  —  4.5  —  6.5  7  2.973  —  2.982\n3-1/4  82.55  4  —  4.875  —  7  7.5  3.223  —  3.232\n3-1/2  88.9  4  —  5.25  —  7.5  8  3.473  —  3.482\n3-3/4  95.25  4  —  5.625  —  8  8.5  3.723  —  3.732\n4  101.6  4  —  6  —  8.5  9  3.973  —  3.982\nlength tolerance (inches), Torqbolt  —  —  —  —  ±0.04 for L 3/4 to 2-1/2; ±0.08 over 2-1/2 to 4  ±0.10 over 4 to 8; ±0.12 over 8 to 16  ±0.18 over 16  —  —  —\n\nFiles elsewhere (not hosted by Xem Studio; license as stated by the publisher):\n- fasten.it: ASME B18.31.2 continuous and double-end studs, inch series: Table 2 (clamping type) and Table 3 (tap end, 1.5D engagement): B min by stud length, Bm, UNC / UNF — web — Reference page; numbers only — https://www.fasten.it/en/norms/norm/asme_b18.31.2\n- Torqbolt: ASME B18.31.2 clamping-type full-body studs: B min in inches and mm, minimum body diameter DS, length tolerance — web — Publisher's page; dimensions are facts — https://torqbolt.com/asme-b18-31-2-clamping-type-full-body-studs-dimensions-standards-specifications\n- Fasteners Clearinghouse: Double-ended studs (ASME B18.31.2) listing — web — Distributor listing; numbers only — https://fastenersclearinghouse.com/ansi-search=ansi-b18.31.2-double-end-studs&us-length=2_1/2&Cat1=PRM249D751F1014;&Cat2=FLF2F52C3045;&Cat7=b18.31.2;\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=double-end-studs-inch-asme-b18-31-2\n",
 "sources": [
  {
   "publisher": "fasten.it",
   "title": "ASME B18.31.2 continuous and double-end studs, inch series: Table 2 (clamping type) and Table 3 (tap end, 1.5D engagement): B min by stud length, Bm, UNC / UNF",
   "url": "https://www.fasten.it/en/norms/norm/asme_b18.31.2",
   "formats": [
    "web"
   ],
   "license": "Reference page; numbers only",
   "license_verified": true,
   "hosted": false
  },
  {
   "publisher": "Torqbolt",
   "title": "ASME B18.31.2 clamping-type full-body studs: B min in inches and mm, minimum body diameter DS, length tolerance",
   "url": "https://torqbolt.com/asme-b18-31-2-clamping-type-full-body-studs-dimensions-standards-specifications",
   "formats": [
    "web"
   ],
   "license": "Publisher's page; dimensions are facts",
   "license_verified": true,
   "hosted": false
  },
  {
   "publisher": "Fasteners Clearinghouse",
   "title": "Double-ended studs (ASME B18.31.2) listing",
   "url": "https://fastenersclearinghouse.com/ansi-search=ansi-b18.31.2-double-end-studs&us-length=2_1/2&Cat1=PRM249D751F1014;&Cat2=FLF2F52C3045;&Cat7=b18.31.2;",
   "formats": [
    "web"
   ],
   "license": "Distributor listing; numbers only",
   "license_verified": true,
   "hosted": false
  }
 ],
 "xem": {
  "status": "not-scanned",
  "sheet_free": true,
  "mesh_price_usd": null,
  "step_price_usd": null,
  "tolerance_mm": null
 },
 "related": [
  "studs-din-938-din-939",
  "threaded-rod-inch-unc-unf-sizes",
  "hex-nuts-inch",
  "hex-bolts-inch",
  "flat-washers-inch",
  "socket-head-cap-screws-inch",
  "lag-screws-hex-inch"
 ],
 "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": [],
 "faq": [
  {
   "q": "How long is the thread on a 1/2-13 clamping stud?",
   "a": "At least 1.25 in at each end for studs up to 10 in long, 1.5 in for 10 to 16 in and 2 in over 16 in (ASME B18.31.2 B min)."
  },
  {
   "q": "What is the tap-end engagement for a 3/4-10 stud?",
   "a": "Bm = 1.125 in nominal (1.5D engagement), B min 1.75 in for L up to 10 in (fasten.it Table 3)."
  },
  {
   "q": "What is the minimum body diameter of a 1/2-13 stud?",
   "a": "0.488 in (UNC); 0.491 in for 1/2-20 UNF (Torqbolt, DS)."
  }
 ],
 "files_license": null,
 "offers": [],
 "markdown": "https://xemstudio.com/objects/double-end-studs-inch-asme-b18-31-2/index.md"
}