{
 "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": "threaded-rod-inch-unc-unf-sizes",
 "name": "Threaded rod, inch: #4 to 4 in, UNC and UNF threads per inch, major diameter in inches and mm, standard lengths",
 "kind": "standard",
 "category": "Hardware",
 "group": "Fasteners",
 "year": null,
 "question": "What are the threads per inch and diameter of 1/4, 3/8, 1/2 and 5/8 inch threaded rod?",
 "tags": [
  "threaded rod",
  "all thread",
  "studding",
  "unc",
  "unf",
  "inch",
  "asme b18.31.3",
  "tpi",
  "tool"
 ],
 "aliases": [
  "1/4 20 threaded rod diameter",
  "3/8-16 threaded rod",
  "1/2-13 all thread",
  "5/8-11 threaded rod",
  "threaded rod sizes inch",
  "all thread tpi chart",
  "threaded rod standard lengths",
  "threaded rod pitch inch",
  "1/4-28 vs 1/4-20 rod",
  "unc threads per inch chart",
  "all thread rod diameter mm",
  "3/4-10 threaded rod",
  "7/16 14 threaded rod",
  "1/2 inch threaded rod mm"
 ],
 "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/threaded-rod-inch-unc-unf-sizes/",
 "sheet_txt": "https://xemstudio.com/objects/threaded-rod-inch-unc-unf-sizes/sheet.txt",
 "sheet": {
  "basis": "ASME B18.31.3 as summarised by Torqbolt (sizes, TPI) and fasten.it (lengths); numbers only",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "notes": [
   "Inch threaded rod (studding, all-thread; ASME B18.31.3) is cut from stock in the UNC (coarse) or UNF (fine) series. Sizes and threads per inch are from Torqbolt's B18.31.3 summary. Its 7/16 row prints 0.4370 in; the fraction 7/16 is 0.4375 in and that is shown. The second source's table (fasten.it) lists the UNC and UNF numbers one row out of step for the fractional sizes (its UNC column reads 18 for 1/4 where Torqbolt has 20, and 16 for 5/16 where Torqbolt has 18), so its TPI numbers are not used.",
   "Nominal diameter is the major diameter of the thread; the major diameter limits that the standard prints were not on a page that could be read. No file is added: a rod is a plain cylinder (Xem draws threads as plain cylinders at the major diameter) and carries no more than the number.",
   "Lengths: ASME B18.31.3 says rods are normally produced in, but not limited to, 3 ft, 6 ft, 10 ft and 12 ft; length tolerance is ±1/2 in for nominal lengths of 6 ft and longer and ±1/4 in under 6 ft (fasten.it's B18.31.3 page). Cut-to-length rods are common.",
   "Metric rod (DIN 976, M3 to M12) is on the threaded-rod-metric-din-976 page. Left out: thread class limits, minor and pitch diameters, mechanical grades (A307, B7, 18-8) and the UNS-size 1-14 for 1 in UNF."
  ],
  "table": {
   "columns": [
    "size",
    "nominal major diameter (in)",
    "major diameter (mm, computed)",
    "UNC",
    "UNC pitch (mm, computed 25.4 ÷ TPI)",
    "UNF"
   ],
   "rows": [
    [
     "#4",
     "0.1120",
     "2.84",
     "4-40",
     "0.635",
     "4-48"
    ],
    [
     "#5",
     "0.1250",
     "3.17",
     "5-40",
     "0.635",
     "5-44"
    ],
    [
     "#6",
     "0.1380",
     "3.51",
     "6-32",
     "0.794",
     "6-40"
    ],
    [
     "#8",
     "0.1640",
     "4.17",
     "8-32",
     "0.794",
     "8-36"
    ],
    [
     "#10",
     "0.1900",
     "4.83",
     "10-24",
     "1.058",
     "10-32"
    ],
    [
     "#12",
     "0.2160",
     "5.49",
     "12-24",
     "1.058",
     "12-28"
    ],
    [
     "1/4",
     "0.2500",
     "6.35",
     "1/4-20",
     "1.270",
     "1/4-28"
    ],
    [
     "5/16",
     "0.3125",
     "7.94",
     "5/16-18",
     "1.411",
     "5/16-24"
    ],
    [
     "3/8",
     "0.3750",
     "9.52",
     "3/8-16",
     "1.587",
     "3/8-24"
    ],
    [
     "7/16",
     "0.4375",
     "11.11",
     "7/16-14",
     "1.814",
     "7/16-20"
    ],
    [
     "1/2",
     "0.5000",
     "12.70",
     "1/2-13",
     "1.954",
     "1/2-20"
    ],
    [
     "9/16",
     "0.5625",
     "14.29",
     "9/16-12",
     "2.117",
     "9/16-18"
    ],
    [
     "5/8",
     "0.6250",
     "15.88",
     "5/8-11",
     "2.309",
     "5/8-18"
    ],
    [
     "3/4",
     "0.7500",
     "19.05",
     "3/4-10",
     "2.540",
     "3/4-16"
    ],
    [
     "7/8",
     "0.8750",
     "22.22",
     "7/8-9",
     "2.822",
     "7/8-14"
    ],
    [
     "1",
     "1.0000",
     "25.40",
     "1-8",
     "3.175",
     "1-12 (the source also prints 1-14 UNS)"
    ],
    [
     "1-1/8",
     "1.1250",
     "28.57",
     "1-1/8-7",
     "3.629",
     "1-12"
    ],
    [
     "1-1/4",
     "1.2500",
     "31.75",
     "1-1/4-7",
     "3.629",
     "1-12"
    ],
    [
     "1-3/8",
     "1.3750",
     "34.92",
     "1-3/8-6",
     "4.233",
     "1-12"
    ],
    [
     "1-1/2",
     "1.5000",
     "38.10",
     "1-1/2-6",
     "4.233",
     "1-12"
    ],
    [
     "1-3/4",
     "1.7500",
     "44.45",
     "1-3/4-5",
     "5.080",
     "-"
    ],
    [
     "2",
     "2.0000",
     "50.80",
     "2-4.5",
     "5.644",
     "-"
    ],
    [
     "2-1/4",
     "2.2500",
     "57.15",
     "2-1/4-4.5",
     "5.644",
     "-"
    ],
    [
     "2-1/2",
     "2.5000",
     "63.50",
     "2-1/2-4",
     "6.350",
     "-"
    ],
    [
     "2-3/4",
     "2.7500",
     "69.85",
     "2-3/4-4",
     "6.350",
     "-"
    ],
    [
     "3",
     "3.0000",
     "76.20",
     "3-4",
     "6.350",
     "-"
    ],
    [
     "3-1/4",
     "3.2500",
     "82.55",
     "3-1/4-4",
     "6.350",
     "-"
    ],
    [
     "3-1/2",
     "3.5000",
     "88.90",
     "3-1/2-4",
     "6.350",
     "-"
    ],
    [
     "3-3/4",
     "3.7500",
     "95.25",
     "3-3/4-4",
     "6.350",
     "-"
    ],
    [
     "4",
     "4.0000",
     "101.60",
     "4-4",
     "6.350",
     "-"
    ]
   ]
  }
 },
 "sheet_text": "Threaded rod, inch: #4 to 4 in, UNC and UNF threads per inch, major diameter in inches and mm, standard lengths — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/threaded-rod-inch-unc-unf-sizes/  (sheet CC BY 4.0)\nBasis: ASME B18.31.3 as summarised by Torqbolt (sizes, TPI) and fasten.it (lengths); numbers only\nCatalog version: 2026-10-20\n\nSizes: see table below\n- Inch threaded rod (studding, all-thread; ASME B18.31.3) is cut from stock in the UNC (coarse) or UNF (fine) series. Sizes and threads per inch are from Torqbolt's B18.31.3 summary. Its 7/16 row prints 0.4370 in; the fraction 7/16 is 0.4375 in and that is shown. The second source's table (fasten.it) lists the UNC and UNF numbers one row out of step for the fractional sizes (its UNC column reads 18 for 1/4 where Torqbolt has 20, and 16 for 5/16 where Torqbolt has 18), so its TPI numbers are not used.\n- Nominal diameter is the major diameter of the thread; the major diameter limits that the standard prints were not on a page that could be read. No file is added: a rod is a plain cylinder (Xem draws threads as plain cylinders at the major diameter) and carries no more than the number.\n- Lengths: ASME B18.31.3 says rods are normally produced in, but not limited to, 3 ft, 6 ft, 10 ft and 12 ft; length tolerance is ±1/2 in for nominal lengths of 6 ft and longer and ±1/4 in under 6 ft (fasten.it's B18.31.3 page). Cut-to-length rods are common.\n- Metric rod (DIN 976, M3 to M12) is on the threaded-rod-metric-din-976 page. Left out: thread class limits, minor and pitch diameters, mechanical grades (A307, B7, 18-8) and the UNS-size 1-14 for 1 in UNF.\n\nsize  nominal major diameter (in)  major diameter (mm, computed)  UNC  UNC pitch (mm, computed 25.4 ÷ TPI)  UNF\n#4  0.1120  2.84  4-40  0.635  4-48\n#5  0.1250  3.17  5-40  0.635  5-44\n#6  0.1380  3.51  6-32  0.794  6-40\n#8  0.1640  4.17  8-32  0.794  8-36\n#10  0.1900  4.83  10-24  1.058  10-32\n#12  0.2160  5.49  12-24  1.058  12-28\n1/4  0.2500  6.35  1/4-20  1.270  1/4-28\n5/16  0.3125  7.94  5/16-18  1.411  5/16-24\n3/8  0.3750  9.52  3/8-16  1.587  3/8-24\n7/16  0.4375  11.11  7/16-14  1.814  7/16-20\n1/2  0.5000  12.70  1/2-13  1.954  1/2-20\n9/16  0.5625  14.29  9/16-12  2.117  9/16-18\n5/8  0.6250  15.88  5/8-11  2.309  5/8-18\n3/4  0.7500  19.05  3/4-10  2.540  3/4-16\n7/8  0.8750  22.22  7/8-9  2.822  7/8-14\n1  1.0000  25.40  1-8  3.175  1-12 (the source also prints 1-14 UNS)\n1-1/8  1.1250  28.57  1-1/8-7  3.629  1-12\n1-1/4  1.2500  31.75  1-1/4-7  3.629  1-12\n1-3/8  1.3750  34.92  1-3/8-6  4.233  1-12\n1-1/2  1.5000  38.10  1-1/2-6  4.233  1-12\n1-3/4  1.7500  44.45  1-3/4-5  5.080  -\n2  2.0000  50.80  2-4.5  5.644  -\n2-1/4  2.2500  57.15  2-1/4-4.5  5.644  -\n2-1/2  2.5000  63.50  2-1/2-4  6.350  -\n2-3/4  2.7500  69.85  2-3/4-4  6.350  -\n3  3.0000  76.20  3-4  6.350  -\n3-1/4  3.2500  82.55  3-1/4-4  6.350  -\n3-1/2  3.5000  88.90  3-1/2-4  6.350  -\n3-3/4  3.7500  95.25  3-3/4-4  6.350  -\n4  4.0000  101.60  4-4  6.350  -\n\nFiles elsewhere (not hosted by Xem Studio; license as stated by the publisher):\n- Torqbolt: ASME B18.31.3 threaded rods: nominal diameters and UNC / UNF threads per inch, #4 to 5 in — web — Publisher's page; dimensions are facts — https://torqbolt.com/asme-b18-31-3-threaded-rods-dimensions-standards-specifications\n- fasten.it: ASME B18.31.3 Standard dimensions for threaded rods, inch series: normal lengths 3, 6, 10, 12 ft and length tolerance — web — Publisher's page; dimensions are facts — https://fasten.it/norms/norm/asme_b18.31.3\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=threaded-rod-inch-unc-unf-sizes\n",
 "sources": [
  {
   "publisher": "Torqbolt",
   "title": "ASME B18.31.3 threaded rods: nominal diameters and UNC / UNF threads per inch, #4 to 5 in",
   "url": "https://torqbolt.com/asme-b18-31-3-threaded-rods-dimensions-standards-specifications",
   "formats": [
    "web"
   ],
   "license": "Publisher's page; dimensions are facts",
   "license_verified": true,
   "hosted": false
  },
  {
   "publisher": "fasten.it",
   "title": "ASME B18.31.3 Standard dimensions for threaded rods, inch series: normal lengths 3, 6, 10, 12 ft and length tolerance",
   "url": "https://fasten.it/norms/norm/asme_b18.31.3",
   "formats": [
    "web"
   ],
   "license": "Publisher's page; dimensions are facts",
   "license_verified": true,
   "hosted": false
  }
 ],
 "xem": {
  "status": "not-scanned",
  "sheet_free": true,
  "mesh_price_usd": null,
  "step_price_usd": null,
  "tolerance_mm": null
 },
 "related": [
  "threaded-rod-metric-din-976",
  "threaded-rods-metric",
  "hex-nuts-inch",
  "nylon-insert-lock-nuts-inch-asme-b18-16-6",
  "bar-stock-sizes-round-square-steel-aluminum",
  "strut-channel-spring-nuts"
 ],
 "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": "1/4-20 rod",
   "exact": "major diameter 6.35, 20 TPI (pitch 1.27 computed)",
   "mates": "1/4-20 UNC nut or tapped hole (see hex-nuts-inch)",
   "fit": "designed",
   "files": "all"
  },
  {
   "feature": "3/8-16 rod",
   "exact": "major diameter 9.525, 16 TPI (pitch 1.5875 computed)",
   "mates": "3/8-16 UNC nut or tapped hole",
   "fit": "designed",
   "files": "all"
  },
  {
   "feature": "1/2-13 rod",
   "exact": "major diameter 12.7, 13 TPI (pitch 1.954 computed)",
   "mates": "1/2-13 UNC nut or tapped hole",
   "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": "How many threads per inch is 1/4 threaded rod?",
   "a": "20 (1/4-20 UNC), or 28 (1/4-28 UNF)."
  },
  {
   "q": "What is the diameter of 1/2-13 threaded rod in mm?",
   "a": "12.7 mm major diameter, 13 threads per inch (pitch 1.954 mm computed)."
  },
  {
   "q": "What lengths does threaded rod come in?",
   "a": "Normally 3, 6, 10 and 12 ft, tolerance ±1/2 in for 6 ft and longer and ±1/4 in below 6 ft (ASME B18.31.3)."
  },
  {
   "q": "What is 3/8-16 threaded rod?",
   "a": "3/8 in (9.525 mm) coarse thread, 16 TPI (pitch 1.588 mm computed)."
  }
 ],
 "files_license": null,
 "offers": [],
 "markdown": "https://xemstudio.com/objects/threaded-rod-inch-unc-unf-sizes/index.md"
}