{
 "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": "torx-hexalobular-drive-sizes-iso-10664",
 "name": "Torx / hexalobular drive sizes T1–T100 (ISO 10664): A and B across lobes, gauge limits for A, B, Ri, Re and depth H, and the screw size each fits",
 "kind": "standard",
 "category": "Hardware",
 "group": "Fasteners",
 "year": null,
 "question": "What are the A and B dimensions of a T20, T25 or T30 hexalobular (Torx) drive, and which Torx size goes with an M4, M5 or M6 screw?",
 "tags": [
  "torx",
  "hexalobular",
  "star drive",
  "six lobe",
  "6 lobe",
  "t25",
  "t20",
  "t30",
  "iso 10664",
  "security torx",
  "tamper resistant torx",
  "pin in torx",
  "torx bit size",
  "storage"
 ],
 "aliases": [
  "torx size chart",
  "t25 torx dimensions",
  "t20 torx a b dimensions",
  "t30 torx size mm",
  "what size torx for m5 screw",
  "t10 torx bit diameter",
  "torx bit sizes",
  "hexalobular socket dimensions",
  "iso 10664 table",
  "torx t15 across lobes",
  "torx t40 size",
  "security torx sizes",
  "tamper resistant torx t20",
  "pin in torx bit",
  "torx tr t25"
 ],
 "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/torx-hexalobular-drive-sizes-iso-10664/",
 "sheet_txt": "https://xemstudio.com/objects/torx-hexalobular-drive-sizes-iso-10664/sheet.txt",
 "sheet": {
  "basis": "ISO 10664:2014 sample pages (Table 1 nominal A and B; Table 3 limiting sizes of the GO gauge), the screw-to-socket pairing from the ISO 14579 / 14580 / 14583 tables on fasten.it, Westfield Fasteners and Aspen Fasteners; numbers only",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "notes": [
   "ISO 10664 specifies the hexalobular internal driving feature (the 'Torx' socket in a screw head and the matching bit). The standard numbers sockets 1 to 100; the trade names T10, T15, T20 and so on use the same numbers, and bit sellers list tamper-resistant bits as T7 to T55 (McMaster-Carr). In ISO 14579 / 14580 / 14583 the screw tables print the number in a 'Socket Nr' column; this page uses 'T' only in search terms.",
   "A is the nominal across the outer lobes and B the nominal across the inner (between-lobe) diameter, both mm, from Table 1 of the 2014 sample pages. For socket 45 the sample prints A = 7.93 while the screw standards (fasten.it, Westfield, Aspen) print A = 7.95 for the same socket; both are shown here (7.93 in the table, 7.95 in the screw-size column of the next page). For the other sockets in the screw tables (6, 8, 10, 15, 20, 25, 30, 50, 55, 60, 70, 80, 90) A matches Table 1.",
   "Limits are Table 3 of the sample pages, the GO gauge that must enter the socket: A, B, Ri (inner radius) and Re (outer radius) as min / max, and H, the gauge height, min / max, all mm. The sample does not define Ri, Re and H in words (they are on Figures 3 and 4, not in the text), so only the printed names are used. Table 4 (the NO-GO gauge for A and Re) stops at socket 80 in the text read and its column alignment was not clear, so it is left out; no nominal Ri or Re is printed in the pages read.",
   "Screw pairing (last column) is read from the ISO 14579 / 14580 / 14583 tables: M2 6, M2.5 8, M3 10, M3.5 15, M4 20, M5 25, M6 30, M8 45, M10 50, and for ISO 14579 only M12 55, M14 60, M16 70, M18 80, M20 90. Other standards and makers (self-tapping, wood and deck screws) pair sizes differently: a Simpson Deck-Drive #10 deck screw uses T25 and a #8 uses T20 (see deck-screws-8-10-simpson-grk).",
   "Security (pin-in, tamper-resistant) Torx: the bit has a hole for the pin in the middle of the screw's socket. McMaster-Carr lists these bits as T7, T8, T9, T10, T15, T20, T25, T27, T30, T35, T40, T45, T50 and T55; the pin diameter and the bit's centre hole are not published as numbers in any source read, so none is shown. Torx Plus and other hexalobular variants are different profiles and are not on this page.",
   "No file: the contour is defined by A, B, Ri, Re and the gauge figures, which are not available as text, so a profile drawn from these numbers alone would be a guess. Hexalobular head screws with true head sizes: hexalobular-socket-screws-iso-14579-14580-14583."
  ],
  "table": {
   "columns": [
    "socket no. (T size)",
    "A nominal",
    "B nominal",
    "GO gauge A min – max",
    "GO gauge B min – max",
    "Ri min – max",
    "Re min – max",
    "H min – max",
    "screw size (ISO 14579 / 14580 / 14583)"
   ],
   "rows": [
    [
     "1",
     "0.9",
     "0.6",
     "0.841 – 0.855",
     "0.592 – 0.607",
     "0.198 – 0.204",
     "0.055 – 0.062",
     "0.64 – 1.14",
     "—"
    ],
    [
     "2",
     "1",
     "0.7",
     "0.953 – 0.967",
     "0.674 – 0.688",
     "0.221 – 0.227",
     "0.065 – 0.072",
     "1.15 – 1.65",
     "—"
    ],
    [
     "3",
     "1.2",
     "0.85",
     "1.131 – 1.145",
     "0.8 – 0.815",
     "0.263 – 0.27",
     "0.078 – 0.085",
     "1.15 – 1.65",
     "—"
    ],
    [
     "4",
     "1.35",
     "1",
     "1.291 – 1.305",
     "0.912 – 0.927",
     "0.305 – 0.312",
     "0.087 – 0.093",
     "1.15 – 1.65",
     "—"
    ],
    [
     "5",
     "1.5",
     "1.1",
     "1.415 – 1.43",
     "1.013 – 1.028",
     "0.318 – 0.342",
     "0.107 – 0.111",
     "1.15 – 1.65",
     "—"
    ],
    [
     "6",
     "1.75",
     "1.27",
     "1.695 – 1.709",
     "1.21 – 1.224",
     "0.371 – 0.396",
     "0.13 – 0.134",
     "1.33 – 1.82",
     "M2"
    ],
    [
     "7",
     "2.1",
     "1.5",
     "2.012 – 2.026",
     "1.437 – 1.453",
     "0.442 – 0.45",
     "0.157 – 0.165",
     "2.54 – 3.05",
     "—"
    ],
    [
     "8",
     "2.4",
     "1.75",
     "2.335 – 2.349",
     "1.672 – 1.686",
     "0.498 – 0.523",
     "0.188 – 0.193",
     "2.54 – 3.05",
     "M2.5"
    ],
    [
     "9",
     "2.6",
     "1.9",
     "2.52 – 2.534",
     "1.809 – 1.823",
     "0.542 – 0.566",
     "0.204 – 0.21",
     "2.79 – 3.3",
     "—"
    ],
    [
     "10",
     "2.8",
     "2.05",
     "2.761 – 2.776",
     "1.979 – 1.993",
     "0.585 – 0.609",
     "0.227 – 0.231",
     "3.05 – 3.56",
     "M3"
    ],
    [
     "15",
     "3.35",
     "2.4",
     "3.295 – 3.309",
     "2.353 – 2.367",
     "0.704 – 0.728",
     "0.265 – 0.269",
     "3.3 – 3.81",
     "M3.5 (ISO 14580 / 14583)"
    ],
    [
     "20",
     "3.95",
     "2.85",
     "3.879 – 3.893",
     "2.764 – 2.778",
     "0.846 – 0.871",
     "0.303 – 0.307",
     "3.56 – 4.07",
     "M4"
    ],
    [
     "25",
     "4.5",
     "3.25",
     "4.451 – 4.465",
     "3.17 – 3.185",
     "0.907 – 0.932",
     "0.371 – 0.378",
     "3.94 – 4.45",
     "M5"
    ],
    [
     "27",
     "5.1",
     "3.68",
     "5.009 – 5.024",
     "3.564 – 3.578",
     "1.095 – 1.12",
     "0.387 – 0.393",
     "4.19 – 4.7",
     "—"
    ],
    [
     "30",
     "5.6",
     "4.05",
     "5.543 – 5.557",
     "3.958 – 3.972",
     "1.182 – 1.206",
     "0.448 – 0.454",
     "4.44 – 4.95",
     "M6"
    ],
    [
     "40",
     "6.75",
     "4.85",
     "6.673 – 6.687",
     "4.766 – 4.78",
     "1.415 – 1.44",
     "0.544 – 0.548",
     "5.08 – 5.59",
     "—"
    ],
    [
     "45",
     "7.93",
     "5.64",
     "7.841 – 7.856",
     "5.555 – 5.57",
     "1.784 – 1.808",
     "0.572 – 0.576",
     "5.71 – 6.22",
     "M8"
    ],
    [
     "50",
     "8.95",
     "6.45",
     "8.857 – 8.872",
     "6.366 – 6.38",
     "1.804 – 1.828",
     "0.773 – 0.777",
     "5.97 – 6.48",
     "M10"
    ],
    [
     "55",
     "11.35",
     "8.05",
     "11.245 – 11.259",
     "7.93 – 7.945",
     "2.657 – 2.682",
     "0.765 – 0.769",
     "6.22 – 6.73",
     "M12 (ISO 14579)"
    ],
    [
     "60",
     "13.45",
     "9.6",
     "13.302 – 13.317",
     "9.49 – 9.504",
     "2.871 – 2.895",
     "1.065 – 1.069",
     "7.68 – 8.17",
     "M14 (ISO 14579)"
    ],
    [
     "70",
     "15.7",
     "11.2",
     "15.588 – 15.603",
     "11.085 – 11.099",
     "3.465 – 3.489",
     "1.192 – 1.196",
     "8.46 – 8.96",
     "M16 (ISO 14579)"
    ],
    [
     "80",
     "17.75",
     "12.8",
     "17.619 – 17.635",
     "12.646 – 12.661",
     "3.625 – 3.629",
     "1.524 – 1.529",
     "9.4 – 9.9",
     "M18 (ISO 14579)"
    ],
    [
     "90",
     "20.2",
     "14.4",
     "20.021 – 20.035",
     "14.232 – 14.246",
     "4.456 – 4.48",
     "1.527 – 1.534",
     "10.06 – 10.56",
     "M20 (ISO 14579)"
    ],
    [
     "100",
     "22.4",
     "16",
     "22.231 – 22.245",
     "15.82 – 15.834",
     "4.913 – 4.937",
     "1.718 – 1.724",
     "10.85 – 11.35",
     "—"
    ]
   ]
  }
 },
 "sheet_text": "Torx / hexalobular drive sizes T1–T100 (ISO 10664): A and B across lobes, gauge limits for A, B, Ri, Re and depth H, and the screw size each fits — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/torx-hexalobular-drive-sizes-iso-10664/  (sheet CC BY 4.0)\nBasis: ISO 10664:2014 sample pages (Table 1 nominal A and B; Table 3 limiting sizes of the GO gauge), the screw-to-socket pairing from the ISO 14579 / 14580 / 14583 tables on fasten.it, Westfield Fasteners and Aspen Fasteners; numbers only\nCatalog version: 2026-10-20\n\nSizes: see table below\n- ISO 10664 specifies the hexalobular internal driving feature (the 'Torx' socket in a screw head and the matching bit). The standard numbers sockets 1 to 100; the trade names T10, T15, T20 and so on use the same numbers, and bit sellers list tamper-resistant bits as T7 to T55 (McMaster-Carr). In ISO 14579 / 14580 / 14583 the screw tables print the number in a 'Socket Nr' column; this page uses 'T' only in search terms.\n- A is the nominal across the outer lobes and B the nominal across the inner (between-lobe) diameter, both mm, from Table 1 of the 2014 sample pages. For socket 45 the sample prints A = 7.93 while the screw standards (fasten.it, Westfield, Aspen) print A = 7.95 for the same socket; both are shown here (7.93 in the table, 7.95 in the screw-size column of the next page). For the other sockets in the screw tables (6, 8, 10, 15, 20, 25, 30, 50, 55, 60, 70, 80, 90) A matches Table 1.\n- Limits are Table 3 of the sample pages, the GO gauge that must enter the socket: A, B, Ri (inner radius) and Re (outer radius) as min / max, and H, the gauge height, min / max, all mm. The sample does not define Ri, Re and H in words (they are on Figures 3 and 4, not in the text), so only the printed names are used. Table 4 (the NO-GO gauge for A and Re) stops at socket 80 in the text read and its column alignment was not clear, so it is left out; no nominal Ri or Re is printed in the pages read.\n- Screw pairing (last column) is read from the ISO 14579 / 14580 / 14583 tables: M2 6, M2.5 8, M3 10, M3.5 15, M4 20, M5 25, M6 30, M8 45, M10 50, and for ISO 14579 only M12 55, M14 60, M16 70, M18 80, M20 90. Other standards and makers (self-tapping, wood and deck screws) pair sizes differently: a Simpson Deck-Drive #10 deck screw uses T25 and a #8 uses T20 (see deck-screws-8-10-simpson-grk).\n- Security (pin-in, tamper-resistant) Torx: the bit has a hole for the pin in the middle of the screw's socket. McMaster-Carr lists these bits as T7, T8, T9, T10, T15, T20, T25, T27, T30, T35, T40, T45, T50 and T55; the pin diameter and the bit's centre hole are not published as numbers in any source read, so none is shown. Torx Plus and other hexalobular variants are different profiles and are not on this page.\n- No file: the contour is defined by A, B, Ri, Re and the gauge figures, which are not available as text, so a profile drawn from these numbers alone would be a guess. Hexalobular head screws with true head sizes: hexalobular-socket-screws-iso-14579-14580-14583.\n\nsocket no. (T size)  A nominal  B nominal  GO gauge A min – max  GO gauge B min – max  Ri min – max  Re min – max  H min – max  screw size (ISO 14579 / 14580 / 14583)\n1  0.9  0.6  0.841 – 0.855  0.592 – 0.607  0.198 – 0.204  0.055 – 0.062  0.64 – 1.14  —\n2  1  0.7  0.953 – 0.967  0.674 – 0.688  0.221 – 0.227  0.065 – 0.072  1.15 – 1.65  —\n3  1.2  0.85  1.131 – 1.145  0.8 – 0.815  0.263 – 0.27  0.078 – 0.085  1.15 – 1.65  —\n4  1.35  1  1.291 – 1.305  0.912 – 0.927  0.305 – 0.312  0.087 – 0.093  1.15 – 1.65  —\n5  1.5  1.1  1.415 – 1.43  1.013 – 1.028  0.318 – 0.342  0.107 – 0.111  1.15 – 1.65  —\n6  1.75  1.27  1.695 – 1.709  1.21 – 1.224  0.371 – 0.396  0.13 – 0.134  1.33 – 1.82  M2\n7  2.1  1.5  2.012 – 2.026  1.437 – 1.453  0.442 – 0.45  0.157 – 0.165  2.54 – 3.05  —\n8  2.4  1.75  2.335 – 2.349  1.672 – 1.686  0.498 – 0.523  0.188 – 0.193  2.54 – 3.05  M2.5\n9  2.6  1.9  2.52 – 2.534  1.809 – 1.823  0.542 – 0.566  0.204 – 0.21  2.79 – 3.3  —\n10  2.8  2.05  2.761 – 2.776  1.979 – 1.993  0.585 – 0.609  0.227 – 0.231  3.05 – 3.56  M3\n15  3.35  2.4  3.295 – 3.309  2.353 – 2.367  0.704 – 0.728  0.265 – 0.269  3.3 – 3.81  M3.5 (ISO 14580 / 14583)\n20  3.95  2.85  3.879 – 3.893  2.764 – 2.778  0.846 – 0.871  0.303 – 0.307  3.56 – 4.07  M4\n25  4.5  3.25  4.451 – 4.465  3.17 – 3.185  0.907 – 0.932  0.371 – 0.378  3.94 – 4.45  M5\n27  5.1  3.68  5.009 – 5.024  3.564 – 3.578  1.095 – 1.12  0.387 – 0.393  4.19 – 4.7  —\n30  5.6  4.05  5.543 – 5.557  3.958 – 3.972  1.182 – 1.206  0.448 – 0.454  4.44 – 4.95  M6\n40  6.75  4.85  6.673 – 6.687  4.766 – 4.78  1.415 – 1.44  0.544 – 0.548  5.08 – 5.59  —\n45  7.93  5.64  7.841 – 7.856  5.555 – 5.57  1.784 – 1.808  0.572 – 0.576  5.71 – 6.22  M8\n50  8.95  6.45  8.857 – 8.872  6.366 – 6.38  1.804 – 1.828  0.773 – 0.777  5.97 – 6.48  M10\n55  11.35  8.05  11.245 – 11.259  7.93 – 7.945  2.657 – 2.682  0.765 – 0.769  6.22 – 6.73  M12 (ISO 14579)\n60  13.45  9.6  13.302 – 13.317  9.49 – 9.504  2.871 – 2.895  1.065 – 1.069  7.68 – 8.17  M14 (ISO 14579)\n70  15.7  11.2  15.588 – 15.603  11.085 – 11.099  3.465 – 3.489  1.192 – 1.196  8.46 – 8.96  M16 (ISO 14579)\n80  17.75  12.8  17.619 – 17.635  12.646 – 12.661  3.625 – 3.629  1.524 – 1.529  9.4 – 9.9  M18 (ISO 14579)\n90  20.2  14.4  20.021 – 20.035  14.232 – 14.246  4.456 – 4.48  1.527 – 1.534  10.06 – 10.56  M20 (ISO 14579)\n100  22.4  16  22.231 – 22.245  15.82 – 15.834  4.913 – 4.937  1.718 – 1.724  10.85 – 11.35  —\n\nFiles elsewhere (not hosted by Xem Studio; license as stated by the publisher):\n- iTeh Standards: ISO 10664:2014 sample pages: Table 1 nominal A and B, Table 3 limiting sizes of the GO gauge (A, B, Ri, Re, H) for socket nos. 1 to 100 — web — Standards-body sample pages; numbers only — https://cdn.standards.iteh.ai/samples/63207/f79670cf0a214881aa40b4822580cce3/ISO-10664-2014.pdf\n- McMaster-Carr: Tamper-resistant (pin-in) Torx bits, T7 to T55 (free STEP/IGES per part, for your own design use; no redistribution) — STEP, IGES, PDF — McMaster-Carr site terms: personal design use, no redistribution [verify license at link] — https://www.mcmaster.com/torx-security-bits\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=torx-hexalobular-drive-sizes-iso-10664\n",
 "sources": [
  {
   "publisher": "iTeh Standards",
   "title": "ISO 10664:2014 sample pages: Table 1 nominal A and B, Table 3 limiting sizes of the GO gauge (A, B, Ri, Re, H) for socket nos. 1 to 100",
   "url": "https://cdn.standards.iteh.ai/samples/63207/f79670cf0a214881aa40b4822580cce3/ISO-10664-2014.pdf",
   "formats": [
    "web"
   ],
   "license": "Standards-body sample pages; numbers only",
   "license_verified": true,
   "hosted": false
  },
  {
   "publisher": "McMaster-Carr",
   "title": "Tamper-resistant (pin-in) Torx bits, T7 to T55 (free STEP/IGES per part, for your own design use; no redistribution)",
   "url": "https://www.mcmaster.com/torx-security-bits",
   "formats": [
    "STEP",
    "IGES",
    "PDF"
   ],
   "license": "McMaster-Carr site terms: personal design use, no redistribution",
   "license_verified": false,
   "hosted": false
  }
 ],
 "xem": {
  "status": "not-scanned",
  "sheet_free": true,
  "mesh_price_usd": null,
  "step_price_usd": null,
  "tolerance_mm": null
 },
 "related": [
  "hexalobular-socket-screws-iso-14579-14580-14583",
  "deck-screws-8-10-simpson-grk",
  "socket-head-cap-screws-metric",
  "machine-screws-metric-pan-cheese-csk",
  "countersunk-screws-metric"
 ],
 "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": "What are the dimensions of a T25 Torx drive?",
   "a": "ISO 10664 socket 25: A 4.5 mm and B 3.25 mm nominal; the GO gauge A runs 4.451 to 4.465 mm and B 3.170 to 3.185 mm."
  },
  {
   "q": "Which Torx size fits an M5 screw?",
   "a": "Socket 25 (T25) in ISO 14579, 14580 and 14583: M3 uses 10, M4 20, M5 25, M6 30, M8 45, M10 50."
  },
  {
   "q": "What is a security Torx (TR, pin-in Torx)?",
   "a": "A hexalobular socket with a pin in the centre; the matching bit has a hole for the pin. McMaster-Carr lists bits T7 to T55. No pin dimension was found in any source read, so none is given here."
  }
 ],
 "files_license": null,
 "offers": [],
 "markdown": "https://xemstudio.com/objects/torx-hexalobular-drive-sizes-iso-10664/index.md"
}