{
 "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": "self-tapping-screws-iso-7049-pan-head",
 "name": "Self-tapping (sheet metal) screws: ISO 7049 pan head ST2.2–ST6.3 and ASME B18.6.4 Type AB thread #2 to 3/8",
 "kind": "standard",
 "category": "Hardware",
 "group": "Fasteners",
 "year": null,
 "question": "What are the pan head size and thread of a #8 or ST4.2 self-tapping sheet metal screw?",
 "tags": [
  "self tapping screw",
  "sheet metal screw",
  "tapping screw",
  "iso 7049",
  "din 7981",
  "type ab screw",
  "asme b18.6.4",
  "pan head",
  "st4.2",
  "fastener"
 ],
 "aliases": [
  "iso 7049 dimensions",
  "din 7981 pan head tapping screw",
  "st4.2 screw head diameter",
  "st2.9 screw dimensions",
  "#8 sheet metal screw head size",
  "sheet metal screw thread size chart",
  "type ab screw threads per inch",
  "#10 sheet metal screw major diameter",
  "st3.5 pan head height",
  "self tapping screw size chart",
  "b18.6.4 type ab",
  "st4.8 screw head"
 ],
 "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/self-tapping-screws-iso-7049-pan-head/",
 "sheet_txt": "https://xemstudio.com/objects/self-tapping-screws-iso-7049-pan-head/sheet.txt",
 "sheet": {
  "basis": "fasteners.eu's ISO 7049 table (pan head, form C and F) and two copies of the Type AB thread table (HB Bolt, citing ASME B18.6.4-1998, and a maker sheet citing B18.6.3-2013); numbers only",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "notes": [
   "ISO 7049 rows are mm, pan head tapping screws with cross recess (types H and Z), forms C (conical point) and F (flat point): thread pitch P, head diameter dk (nominal = max, with min), head height k (nominal = max, with min), r max (under-head radius), rf (head crown radius, 'approx.') and the cross-recess number. ST3.9 is in brackets in the standard (non-preferred), as on the page. The page also tabulates recess depths, the dimension m (approx.) and the minimum / maximum screw length by form, which are not repeated here. Pitch 'a max' equals the pitch in every column. The ST thread itself (ISO 1478) major and minor diameters were not in the source read.",
   "Type AB rows are inches: nominal size #2 to 3/8, basic screw diameter D, threads per inch, major diameter max / min, minor diameter max / min. HB Bolt cites ASME B18.6.4-1998 and the second sheet cites B18.6.3-2013; the numbers are identical on both. The second sheet labels the two columns after the diameters as 'min practical screw length' for 90° (flat-under-head) and countersunk heads and the last as minimum torsional strength in lb-in for steel screws; HB Bolt's headers were jumbled, so the labels come from that second sheet. Length tolerance (both): ±0.03 in up to 1 in, ±0.05 in over 1 in.",
   "Pan head dimensions for the inch Type AB / A screws (B18.6.4 pan head tables) were not in the sources read; none is given. The ST-size to Type AB size correspondence (for example ST4.2 versus #8) is not printed by the sources read and is not claimed. Pilot holes for these screws: sheet-metal-screw-pilot-holes; plastics: plastic-thread-forming-screw-holes.",
   "No file: the pan head crown shape is given by rf 'approx.' and the recess profile is not drawn here, and the thread is a plain cylinder; the brief rule against plain shapes applies. McMaster-Carr sells sheet metal screws with per-part STEP; the category is linked, not copied."
  ],
  "table": {
   "columns": [
    "standard",
    "size",
    "pitch / TPI",
    "head dia dk max / min (mm)",
    "head height k max / min (mm)",
    "r max, rf (mm) | major, minor (in)",
    "recess",
    "min practical length (in)",
    "min torsional strength"
   ],
   "rows": [
    [
     "ISO 7049 pan head (mm)",
     "ST2.2",
     "0.8 mm",
     "4.2 / 3.9",
     "1.8 / 1.55",
     "r max 0.3; rf ≈ 3.4",
     "cross recess No. 1",
     "—",
     "—"
    ],
    [
     "ISO 7049 pan head (mm)",
     "ST2.9",
     "1.1 mm",
     "5.6 / 5.3",
     "2.2 / 1.95",
     "r max 0.4; rf ≈ 4.4",
     "cross recess No. 1",
     "—",
     "—"
    ],
    [
     "ISO 7049 pan head (mm)",
     "ST3.5",
     "1.3 mm",
     "6.9 / 6.54",
     "2.6 / 2.35",
     "r max 0.5; rf ≈ 5.4",
     "cross recess No. 2",
     "—",
     "—"
    ],
    [
     "ISO 7049 pan head (mm)",
     "(ST3.9)",
     "1.3 mm",
     "7.5 / 7.14",
     "2.8 / 2.55",
     "r max 0.5; rf ≈ 5.8",
     "cross recess No. 2",
     "—",
     "—"
    ],
    [
     "ISO 7049 pan head (mm)",
     "ST4.2",
     "1.4 mm",
     "8.2 / 7.84",
     "3.05 / 2.75",
     "r max 0.6; rf ≈ 6.2",
     "cross recess No. 2",
     "—",
     "—"
    ],
    [
     "ISO 7049 pan head (mm)",
     "ST4.8",
     "1.6 mm",
     "9.5 / 9.14",
     "3.55 / 3.25",
     "r max 0.7; rf ≈ 7.2",
     "cross recess No. 2",
     "—",
     "—"
    ],
    [
     "ISO 7049 pan head (mm)",
     "ST5.5",
     "1.8 mm",
     "10.8 / 10.37",
     "3.95 / 3.65",
     "r max 0.8; rf ≈ 8.2",
     "cross recess No. 3",
     "—",
     "—"
    ],
    [
     "ISO 7049 pan head (mm)",
     "ST6.3",
     "1.8 mm",
     "12.5 / 12.07",
     "4.55 / 4.25",
     "r max 0.9; rf ≈ 9.5",
     "cross recess No. 3",
     "—",
     "—"
    ],
    [
     "ASME B18.6.4 Type AB thread (in)",
     "#2",
     "32 TPI; basic .0860",
     "—",
     "—",
     "major .088 / .082; minor .064 / .060",
     "—",
     "3/16 (90° heads); 7/32 (csk heads)",
     "4 lb-in (steel)"
    ],
    [
     "ASME B18.6.4 Type AB thread (in)",
     "#3",
     "28 TPI; basic .0990",
     "—",
     "—",
     "major .101 / .095; minor .075 / .071",
     "—",
     "3/16 (90° heads); 1/4 (csk heads)",
     "9 lb-in (steel)"
    ],
    [
     "ASME B18.6.4 Type AB thread (in)",
     "#4",
     "24 TPI; basic .1120",
     "—",
     "—",
     "major .114 / .108; minor .086 / .082",
     "—",
     "7/32 (90° heads); 9/32 (csk heads)",
     "13 lb-in (steel)"
    ],
    [
     "ASME B18.6.4 Type AB thread (in)",
     "#5",
     "20 TPI; basic .1250",
     "—",
     "—",
     "major .130 / .123; minor .094 / .090",
     "—",
     "1/4 (90° heads); 5/16 (csk heads)",
     "18 lb-in (steel)"
    ],
    [
     "ASME B18.6.4 Type AB thread (in)",
     "#6",
     "20 TPI; basic .1380",
     "—",
     "—",
     "major .139 / .132; minor .104 / .099",
     "—",
     "9/32 (90° heads); 11/32 (csk heads)",
     "24 lb-in (steel)"
    ],
    [
     "ASME B18.6.4 Type AB thread (in)",
     "#7",
     "19 TPI; basic .1510",
     "—",
     "—",
     "major .154 / .147; minor .115 / .109",
     "—",
     "5/16 (90° heads); 3/8 (csk heads)",
     "30 lb-in (steel)"
    ],
    [
     "ASME B18.6.4 Type AB thread (in)",
     "#8",
     "18 TPI; basic .1640",
     "—",
     "—",
     "major .166 / .159; minor .122 / .116",
     "—",
     "5/16 (90° heads); 3/8 (csk heads)",
     "39 lb-in (steel)"
    ],
    [
     "ASME B18.6.4 Type AB thread (in)",
     "#10",
     "16 TPI; basic .1900",
     "—",
     "—",
     "major .189 / .182; minor .141 / .135",
     "—",
     "3/8 (90° heads); 7/16 (csk heads)",
     "56 lb-in (steel)"
    ],
    [
     "ASME B18.6.4 Type AB thread (in)",
     "#12",
     "14 TPI; basic .2160",
     "—",
     "—",
     "major .215 / .208; minor .164 / .157",
     "—",
     "7/16 (90° heads); 21/32 (csk heads)",
     "88 lb-in (steel)"
    ],
    [
     "ASME B18.6.4 Type AB thread (in)",
     "1/4",
     "14 TPI; basic .2500",
     "—",
     "—",
     "major .246 / .237; minor .192 / .185",
     "—",
     "1/2 (90° heads); 19/32 (csk heads)",
     "142 lb-in (steel)"
    ],
    [
     "ASME B18.6.4 Type AB thread (in)",
     "5/16",
     "12 TPI; basic .3125",
     "—",
     "—",
     "major .315 / .306; minor .244 / .236",
     "—",
     "5/8 (90° heads); 3/4 (csk heads)",
     "290 lb-in (steel)"
    ],
    [
     "ASME B18.6.4 Type AB thread (in)",
     "3/8",
     "12 TPI; basic .3750",
     "—",
     "—",
     "major .380 / .371; minor .309 / .299",
     "—",
     "3/4 (90° heads); 29/32 (csk heads)",
     "590 lb-in (steel)"
    ]
   ]
  }
 },
 "sheet_text": "Self-tapping (sheet metal) screws: ISO 7049 pan head ST2.2–ST6.3 and ASME B18.6.4 Type AB thread #2 to 3/8 — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/self-tapping-screws-iso-7049-pan-head/  (sheet CC BY 4.0)\nBasis: fasteners.eu's ISO 7049 table (pan head, form C and F) and two copies of the Type AB thread table (HB Bolt, citing ASME B18.6.4-1998, and a maker sheet citing B18.6.3-2013); numbers only\nCatalog version: 2026-10-20\n\nSizes: see table below\n- ISO 7049 rows are mm, pan head tapping screws with cross recess (types H and Z), forms C (conical point) and F (flat point): thread pitch P, head diameter dk (nominal = max, with min), head height k (nominal = max, with min), r max (under-head radius), rf (head crown radius, 'approx.') and the cross-recess number. ST3.9 is in brackets in the standard (non-preferred), as on the page. The page also tabulates recess depths, the dimension m (approx.) and the minimum / maximum screw length by form, which are not repeated here. Pitch 'a max' equals the pitch in every column. The ST thread itself (ISO 1478) major and minor diameters were not in the source read.\n- Type AB rows are inches: nominal size #2 to 3/8, basic screw diameter D, threads per inch, major diameter max / min, minor diameter max / min. HB Bolt cites ASME B18.6.4-1998 and the second sheet cites B18.6.3-2013; the numbers are identical on both. The second sheet labels the two columns after the diameters as 'min practical screw length' for 90° (flat-under-head) and countersunk heads and the last as minimum torsional strength in lb-in for steel screws; HB Bolt's headers were jumbled, so the labels come from that second sheet. Length tolerance (both): ±0.03 in up to 1 in, ±0.05 in over 1 in.\n- Pan head dimensions for the inch Type AB / A screws (B18.6.4 pan head tables) were not in the sources read; none is given. The ST-size to Type AB size correspondence (for example ST4.2 versus #8) is not printed by the sources read and is not claimed. Pilot holes for these screws: sheet-metal-screw-pilot-holes; plastics: plastic-thread-forming-screw-holes.\n- No file: the pan head crown shape is given by rf 'approx.' and the recess profile is not drawn here, and the thread is a plain cylinder; the brief rule against plain shapes applies. McMaster-Carr sells sheet metal screws with per-part STEP; the category is linked, not copied.\n\nstandard  size  pitch / TPI  head dia dk max / min (mm)  head height k max / min (mm)  r max, rf (mm) | major, minor (in)  recess  min practical length (in)  min torsional strength\nISO 7049 pan head (mm)  ST2.2  0.8 mm  4.2 / 3.9  1.8 / 1.55  r max 0.3; rf ≈ 3.4  cross recess No. 1  —  —\nISO 7049 pan head (mm)  ST2.9  1.1 mm  5.6 / 5.3  2.2 / 1.95  r max 0.4; rf ≈ 4.4  cross recess No. 1  —  —\nISO 7049 pan head (mm)  ST3.5  1.3 mm  6.9 / 6.54  2.6 / 2.35  r max 0.5; rf ≈ 5.4  cross recess No. 2  —  —\nISO 7049 pan head (mm)  (ST3.9)  1.3 mm  7.5 / 7.14  2.8 / 2.55  r max 0.5; rf ≈ 5.8  cross recess No. 2  —  —\nISO 7049 pan head (mm)  ST4.2  1.4 mm  8.2 / 7.84  3.05 / 2.75  r max 0.6; rf ≈ 6.2  cross recess No. 2  —  —\nISO 7049 pan head (mm)  ST4.8  1.6 mm  9.5 / 9.14  3.55 / 3.25  r max 0.7; rf ≈ 7.2  cross recess No. 2  —  —\nISO 7049 pan head (mm)  ST5.5  1.8 mm  10.8 / 10.37  3.95 / 3.65  r max 0.8; rf ≈ 8.2  cross recess No. 3  —  —\nISO 7049 pan head (mm)  ST6.3  1.8 mm  12.5 / 12.07  4.55 / 4.25  r max 0.9; rf ≈ 9.5  cross recess No. 3  —  —\nASME B18.6.4 Type AB thread (in)  #2  32 TPI; basic .0860  —  —  major .088 / .082; minor .064 / .060  —  3/16 (90° heads); 7/32 (csk heads)  4 lb-in (steel)\nASME B18.6.4 Type AB thread (in)  #3  28 TPI; basic .0990  —  —  major .101 / .095; minor .075 / .071  —  3/16 (90° heads); 1/4 (csk heads)  9 lb-in (steel)\nASME B18.6.4 Type AB thread (in)  #4  24 TPI; basic .1120  —  —  major .114 / .108; minor .086 / .082  —  7/32 (90° heads); 9/32 (csk heads)  13 lb-in (steel)\nASME B18.6.4 Type AB thread (in)  #5  20 TPI; basic .1250  —  —  major .130 / .123; minor .094 / .090  —  1/4 (90° heads); 5/16 (csk heads)  18 lb-in (steel)\nASME B18.6.4 Type AB thread (in)  #6  20 TPI; basic .1380  —  —  major .139 / .132; minor .104 / .099  —  9/32 (90° heads); 11/32 (csk heads)  24 lb-in (steel)\nASME B18.6.4 Type AB thread (in)  #7  19 TPI; basic .1510  —  —  major .154 / .147; minor .115 / .109  —  5/16 (90° heads); 3/8 (csk heads)  30 lb-in (steel)\nASME B18.6.4 Type AB thread (in)  #8  18 TPI; basic .1640  —  —  major .166 / .159; minor .122 / .116  —  5/16 (90° heads); 3/8 (csk heads)  39 lb-in (steel)\nASME B18.6.4 Type AB thread (in)  #10  16 TPI; basic .1900  —  —  major .189 / .182; minor .141 / .135  —  3/8 (90° heads); 7/16 (csk heads)  56 lb-in (steel)\nASME B18.6.4 Type AB thread (in)  #12  14 TPI; basic .2160  —  —  major .215 / .208; minor .164 / .157  —  7/16 (90° heads); 21/32 (csk heads)  88 lb-in (steel)\nASME B18.6.4 Type AB thread (in)  1/4  14 TPI; basic .2500  —  —  major .246 / .237; minor .192 / .185  —  1/2 (90° heads); 19/32 (csk heads)  142 lb-in (steel)\nASME B18.6.4 Type AB thread (in)  5/16  12 TPI; basic .3125  —  —  major .315 / .306; minor .244 / .236  —  5/8 (90° heads); 3/4 (csk heads)  290 lb-in (steel)\nASME B18.6.4 Type AB thread (in)  3/8  12 TPI; basic .3750  —  —  major .380 / .371; minor .309 / .299  —  3/4 (90° heads); 29/32 (csk heads)  590 lb-in (steel)\n\nFiles elsewhere (not hosted by Xem Studio; license as stated by the publisher):\n- fasteners.eu: ISO 7049 pan head tapping screws with cross recess H and Z, form C and F: P, a, dk, k, r, rf, recess, ST2.2 to ST6.3 and lengths — web — Reference page; numbers only — https://www.fasteners.eu/standards/ISO/7049/\n- HB Bolt: Type AB tapping screw thread (ASME B18.6.4-1998): basic diameter, threads per inch, major and minor diameter max / min, #2 to 3/8 — web — Maker cut sheet; numbers only. Headers jumbled in the text read — https://www.hbbolt.com/_Product_Cut_Sheets/TypeABPointInfo.pdf\n- Cold-forged fastener maker sheet (hosted on a Shopify CDN, maker not named in the text read): Threads for self-tapping screws, Type AB: same table with labelled columns including minimum practical screw length (90° and countersunk heads) and minimum torsional strength; cites ASME B18.6.3-2013 — web — Maker datasheet; numbers only — https://cdn2.shopify.com/s/files/1/0056/7856/3437/files/SttypeAB.pdf\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=self-tapping-screws-iso-7049-pan-head\n",
 "sources": [
  {
   "publisher": "fasteners.eu",
   "title": "ISO 7049 pan head tapping screws with cross recess H and Z, form C and F: P, a, dk, k, r, rf, recess, ST2.2 to ST6.3 and lengths",
   "url": "https://www.fasteners.eu/standards/ISO/7049/",
   "formats": [
    "web"
   ],
   "license": "Reference page; numbers only",
   "license_verified": true,
   "hosted": false
  },
  {
   "publisher": "HB Bolt",
   "title": "Type AB tapping screw thread (ASME B18.6.4-1998): basic diameter, threads per inch, major and minor diameter max / min, #2 to 3/8",
   "url": "https://www.hbbolt.com/_Product_Cut_Sheets/TypeABPointInfo.pdf",
   "formats": [
    "web"
   ],
   "license": "Maker cut sheet; numbers only. Headers jumbled in the text read",
   "license_verified": true,
   "hosted": false
  },
  {
   "publisher": "Cold-forged fastener maker sheet (hosted on a Shopify CDN, maker not named in the text read)",
   "title": "Threads for self-tapping screws, Type AB: same table with labelled columns including minimum practical screw length (90° and countersunk heads) and minimum torsional strength; cites ASME B18.6.3-2013",
   "url": "https://cdn2.shopify.com/s/files/1/0056/7856/3437/files/SttypeAB.pdf",
   "formats": [
    "web"
   ],
   "license": "Maker datasheet; 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": [
  "sheet-metal-screw-pilot-holes",
  "plastic-thread-forming-screw-holes",
  "imperial-machine-screws",
  "wood-screws-flat-head-inch",
  "rivet-nuts-flat-head",
  "blind-pop-rivets-dome-head",
  "self-drilling-screws-din-7504-heads",
  "tek-self-drilling-screw-drill-points"
 ],
 "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": "Type AB thread",
   "exact": "#8: 18 TPI, major .166 / .159 in, minor .122 / .116 in; #10: 16 TPI, major .189 / .182 in, minor .141 / .135 in (ASME B18.6.4)",
   "mates": "pilot hole in sheet metal from sheet-metal-screw-pilot-holes (AFT: #8 drill 29, .1360 in; #10 drill 21, .1590 in)",
   "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 is the head diameter of an ST4.2 pan head screw?",
   "a": "ISO 7049: dk 8.2 mm max and 7.84 mm min, head height k 3.05 mm max and 2.75 mm min, pitch 1.4 mm, cross recess No. 2 (fasteners.eu)."
  },
  {
   "q": "How many threads per inch is a #8 Type AB screw?",
   "a": "18 TPI, major diameter .166 / .159 in and minor .122 / .116 in (HB Bolt, ASME B18.6.4; the same on a second sheet)."
  },
  {
   "q": "What does ST mean on a screw?",
   "a": "ST is the ISO 1478 tapping-screw thread series, for example ST4.2 with pitch 1.4 mm in ISO 7049; its major and minor diameters were not in the sources read here."
  }
 ],
 "files_license": null,
 "offers": [],
 "markdown": "https://xemstudio.com/objects/self-tapping-screws-iso-7049-pan-head/index.md"
}