{
 "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": "rigid-imc-emt-conduit-sizes-to-4-in",
 "name": "Rigid (RMC), IMC and EMT conduit sizes to 4 in: outside diameter, wall and inside diameter by trade size, inches and mm",
 "kind": "standard",
 "category": "Tri-clamp & pipe",
 "group": "Pipe, tube & threads",
 "year": null,
 "question": "What is the outside diameter of 1/2 inch rigid conduit, IMC, and 3 inch EMT?",
 "tags": [
  "conduit",
  "rigid conduit",
  "rmc",
  "grc",
  "imc",
  "emt",
  "trade size",
  "electrical",
  "ansi c80",
  "tool"
 ],
 "aliases": [
  "rigid conduit od",
  "1/2 rigid conduit outside diameter",
  "3/4 rmc od",
  "imc conduit od",
  "1 inch imc outside diameter",
  "conduit od chart",
  "rmc vs emt od",
  "3 inch emt od",
  "conduit trade size chart",
  "metric designator conduit",
  "4 inch rigid conduit diameter",
  "emt 2-1/2 od",
  "conduit wall thickness",
  "rigid conduit dimensions 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/rigid-imc-emt-conduit-sizes-to-4-in/",
 "sheet_txt": "https://xemstudio.com/objects/rigid-imc-emt-conduit-sizes-to-4-in/sheet.txt",
 "sheet": {
  "basis": "Wheatland Tube (RMC OD and ID), BIA conduit catalog (walls, EMT 2-1/2 to 4), Allied Tube IMC cut sheet; numbers only, disagreements shown",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "notes": [
   "Rigid metal conduit (RMC, also called GRC, galvanized rigid conduit): OD and ID by trade size from Wheatland Tube's submittal sheet (ANSI C80.1, UL 6; its OD tolerance is ±0.015 in for 1/2 to 1-1/2 in and ±1% for 2 in and up); walls from BIA's conduit page. BIA prints the rigid OD rounded to 0.1 in (0.8, 1.0, 1.3 ...) so its OD is not used; Wheatland's nominal ID agrees with BIA's wall on every row (OD − ID = 2 × wall to 0.0015 in).",
   "IMC (intermediate metal conduit, ANSI C80.6): Allied Tube's cut sheet gives OD and wall; BIA's catalog page prints a thicker wall for every size (for 1/2 in: Allied 0.070 in, BIA 0.078 in; for 4 in: 0.140 and 0.150), so both are shown and the ID is computed from Allied's wall. Check the maker's sheet for the one you buy. BIA's rounded IMC OD is not used.",
   "EMT sizes 1/2 to 2 in are on the emt-conduit page (OD 0.706 to 2.197 in); this page adds 2-1/2 to 4 in from BIA's conduit page (ANSI C80.3): the wall is printed there and the ID is computed. Only one source was read for them. BIA's EMT values for 1/2 to 2 in agree with the emt-conduit page.",
   "Trade size (and the metric designator 16 to 155) identifies the size; per the Steel Tube Institute 'they are for identification purposes only and are not actual dimensions'. Knockout diameters for the same trade sizes are on the knockout page.",
   "Left out: thread dimensions and lengths of rigid and IMC (the threads are NPT-style conduit threads with their own lengths), bend radii, coupling and fitting dimensions: the set-screw EMT connector and coupling sheets read (EMCO ERI, O-Z/Gedney) print drawing dimensions as A, B, C without saying which each is, so none is tabulated. No files: a conduit stick is a plain tube; the OD and wall are the numbers."
  ],
  "table": {
   "columns": [
    "type",
    "trade size (in)",
    "metric designator",
    "OD (in)",
    "OD (mm)",
    "wall (in)",
    "wall, second source (in)",
    "ID (in)"
   ],
   "rows": [
    [
     "rigid (RMC / GRC, ANSI C80.1)",
     "1/2",
     "16",
     "0.840",
     "21.34",
     "0.104",
     "-",
     "0.632 (printed)"
    ],
    [
     "rigid (RMC / GRC, ANSI C80.1)",
     "3/4",
     "21",
     "1.050",
     "26.67",
     "0.107",
     "-",
     "0.836 (printed)"
    ],
    [
     "rigid (RMC / GRC, ANSI C80.1)",
     "1",
     "27",
     "1.315",
     "33.40",
     "0.126",
     "-",
     "1.063 (printed)"
    ],
    [
     "rigid (RMC / GRC, ANSI C80.1)",
     "1-1/4",
     "35",
     "1.660",
     "42.16",
     "0.133",
     "-",
     "1.394 (printed)"
    ],
    [
     "rigid (RMC / GRC, ANSI C80.1)",
     "1-1/2",
     "41",
     "1.900",
     "48.26",
     "0.138",
     "-",
     "1.624 (printed)"
    ],
    [
     "rigid (RMC / GRC, ANSI C80.1)",
     "2",
     "53",
     "2.375",
     "60.33",
     "0.146",
     "-",
     "2.083 (printed)"
    ],
    [
     "rigid (RMC / GRC, ANSI C80.1)",
     "2-1/2",
     "63",
     "2.875",
     "73.03",
     "0.193",
     "-",
     "2.489 (printed)"
    ],
    [
     "rigid (RMC / GRC, ANSI C80.1)",
     "3",
     "78",
     "3.500",
     "88.90",
     "0.205",
     "-",
     "3.090 (printed)"
    ],
    [
     "rigid (RMC / GRC, ANSI C80.1)",
     "3-1/2",
     "91",
     "4.000",
     "101.60",
     "0.215",
     "-",
     "3.570 (printed)"
    ],
    [
     "rigid (RMC / GRC, ANSI C80.1)",
     "4",
     "103",
     "4.500",
     "114.30",
     "0.225",
     "-",
     "4.050 (printed)"
    ],
    [
     "rigid (RMC / GRC, ANSI C80.1)",
     "5",
     "129",
     "5.563",
     "141.30",
     "0.245",
     "-",
     "5.073 (printed)"
    ],
    [
     "rigid (RMC / GRC, ANSI C80.1)",
     "6",
     "155",
     "6.625",
     "168.28",
     "0.266",
     "-",
     "6.093 (printed)"
    ],
    [
     "IMC (ANSI C80.6)",
     "1/2",
     "16",
     "0.815",
     "20.70",
     "0.070 (Allied)",
     "0.078 (BIA)",
     "0.675 (computed, Allied wall)"
    ],
    [
     "IMC (ANSI C80.6)",
     "3/4",
     "21",
     "1.029",
     "26.13",
     "0.075 (Allied)",
     "0.083 (BIA)",
     "0.879 (computed, Allied wall)"
    ],
    [
     "IMC (ANSI C80.6)",
     "1",
     "27",
     "1.290",
     "32.76",
     "0.085 (Allied)",
     "0.093 (BIA)",
     "1.120 (computed, Allied wall)"
    ],
    [
     "IMC (ANSI C80.6)",
     "1-1/4",
     "35",
     "1.638",
     "41.60",
     "0.085 (Allied)",
     "0.095 (BIA)",
     "1.468 (computed, Allied wall)"
    ],
    [
     "IMC (ANSI C80.6)",
     "1-1/2",
     "41",
     "1.883",
     "47.82",
     "0.090 (Allied)",
     "0.100 (BIA)",
     "1.703 (computed, Allied wall)"
    ],
    [
     "IMC (ANSI C80.6)",
     "2",
     "53",
     "2.360",
     "59.94",
     "0.095 (Allied)",
     "0.105 (BIA)",
     "2.170 (computed, Allied wall)"
    ],
    [
     "IMC (ANSI C80.6)",
     "2-1/2",
     "63",
     "2.857",
     "72.56",
     "0.140 (Allied)",
     "0.150 (BIA)",
     "2.577 (computed, Allied wall)"
    ],
    [
     "IMC (ANSI C80.6)",
     "3",
     "78",
     "3.476",
     "88.29",
     "0.140 (Allied)",
     "0.150 (BIA)",
     "3.196 (computed, Allied wall)"
    ],
    [
     "IMC (ANSI C80.6)",
     "3-1/2",
     "91",
     "3.971",
     "100.86",
     "0.140 (Allied)",
     "0.150 (BIA)",
     "3.691 (computed, Allied wall)"
    ],
    [
     "IMC (ANSI C80.6)",
     "4",
     "103",
     "4.466",
     "113.43",
     "0.140 (Allied)",
     "0.150 (BIA)",
     "4.186 (computed, Allied wall)"
    ],
    [
     "EMT (ANSI C80.3), sizes above the emt-conduit page",
     "2-1/2",
     "63",
     "2.875",
     "73.00",
     "0.072 (BIA)",
     "-",
     "2.731 (computed)"
    ],
    [
     "EMT (ANSI C80.3), sizes above the emt-conduit page",
     "3",
     "78",
     "3.500",
     "88.90",
     "0.072 (BIA)",
     "-",
     "3.356 (computed)"
    ],
    [
     "EMT (ANSI C80.3), sizes above the emt-conduit page",
     "3-1/2",
     "91",
     "4.000",
     "101.60",
     "0.083 (BIA)",
     "-",
     "3.834 (computed)"
    ],
    [
     "EMT (ANSI C80.3), sizes above the emt-conduit page",
     "4",
     "103",
     "4.500",
     "114.30",
     "0.083 (BIA)",
     "-",
     "4.334 (computed)"
    ]
   ]
  }
 },
 "sheet_text": "Rigid (RMC), IMC and EMT conduit sizes to 4 in: outside diameter, wall and inside diameter by trade size, inches and mm — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/rigid-imc-emt-conduit-sizes-to-4-in/  (sheet CC BY 4.0)\nBasis: Wheatland Tube (RMC OD and ID), BIA conduit catalog (walls, EMT 2-1/2 to 4), Allied Tube IMC cut sheet; numbers only, disagreements shown\nCatalog version: 2026-10-20\n\nSizes: see table below\n- Rigid metal conduit (RMC, also called GRC, galvanized rigid conduit): OD and ID by trade size from Wheatland Tube's submittal sheet (ANSI C80.1, UL 6; its OD tolerance is ±0.015 in for 1/2 to 1-1/2 in and ±1% for 2 in and up); walls from BIA's conduit page. BIA prints the rigid OD rounded to 0.1 in (0.8, 1.0, 1.3 ...) so its OD is not used; Wheatland's nominal ID agrees with BIA's wall on every row (OD − ID = 2 × wall to 0.0015 in).\n- IMC (intermediate metal conduit, ANSI C80.6): Allied Tube's cut sheet gives OD and wall; BIA's catalog page prints a thicker wall for every size (for 1/2 in: Allied 0.070 in, BIA 0.078 in; for 4 in: 0.140 and 0.150), so both are shown and the ID is computed from Allied's wall. Check the maker's sheet for the one you buy. BIA's rounded IMC OD is not used.\n- EMT sizes 1/2 to 2 in are on the emt-conduit page (OD 0.706 to 2.197 in); this page adds 2-1/2 to 4 in from BIA's conduit page (ANSI C80.3): the wall is printed there and the ID is computed. Only one source was read for them. BIA's EMT values for 1/2 to 2 in agree with the emt-conduit page.\n- Trade size (and the metric designator 16 to 155) identifies the size; per the Steel Tube Institute 'they are for identification purposes only and are not actual dimensions'. Knockout diameters for the same trade sizes are on the knockout page.\n- Left out: thread dimensions and lengths of rigid and IMC (the threads are NPT-style conduit threads with their own lengths), bend radii, coupling and fitting dimensions: the set-screw EMT connector and coupling sheets read (EMCO ERI, O-Z/Gedney) print drawing dimensions as A, B, C without saying which each is, so none is tabulated. No files: a conduit stick is a plain tube; the OD and wall are the numbers.\n\ntype  trade size (in)  metric designator  OD (in)  OD (mm)  wall (in)  wall, second source (in)  ID (in)\nrigid (RMC / GRC, ANSI C80.1)  1/2  16  0.840  21.34  0.104  -  0.632 (printed)\nrigid (RMC / GRC, ANSI C80.1)  3/4  21  1.050  26.67  0.107  -  0.836 (printed)\nrigid (RMC / GRC, ANSI C80.1)  1  27  1.315  33.40  0.126  -  1.063 (printed)\nrigid (RMC / GRC, ANSI C80.1)  1-1/4  35  1.660  42.16  0.133  -  1.394 (printed)\nrigid (RMC / GRC, ANSI C80.1)  1-1/2  41  1.900  48.26  0.138  -  1.624 (printed)\nrigid (RMC / GRC, ANSI C80.1)  2  53  2.375  60.33  0.146  -  2.083 (printed)\nrigid (RMC / GRC, ANSI C80.1)  2-1/2  63  2.875  73.03  0.193  -  2.489 (printed)\nrigid (RMC / GRC, ANSI C80.1)  3  78  3.500  88.90  0.205  -  3.090 (printed)\nrigid (RMC / GRC, ANSI C80.1)  3-1/2  91  4.000  101.60  0.215  -  3.570 (printed)\nrigid (RMC / GRC, ANSI C80.1)  4  103  4.500  114.30  0.225  -  4.050 (printed)\nrigid (RMC / GRC, ANSI C80.1)  5  129  5.563  141.30  0.245  -  5.073 (printed)\nrigid (RMC / GRC, ANSI C80.1)  6  155  6.625  168.28  0.266  -  6.093 (printed)\nIMC (ANSI C80.6)  1/2  16  0.815  20.70  0.070 (Allied)  0.078 (BIA)  0.675 (computed, Allied wall)\nIMC (ANSI C80.6)  3/4  21  1.029  26.13  0.075 (Allied)  0.083 (BIA)  0.879 (computed, Allied wall)\nIMC (ANSI C80.6)  1  27  1.290  32.76  0.085 (Allied)  0.093 (BIA)  1.120 (computed, Allied wall)\nIMC (ANSI C80.6)  1-1/4  35  1.638  41.60  0.085 (Allied)  0.095 (BIA)  1.468 (computed, Allied wall)\nIMC (ANSI C80.6)  1-1/2  41  1.883  47.82  0.090 (Allied)  0.100 (BIA)  1.703 (computed, Allied wall)\nIMC (ANSI C80.6)  2  53  2.360  59.94  0.095 (Allied)  0.105 (BIA)  2.170 (computed, Allied wall)\nIMC (ANSI C80.6)  2-1/2  63  2.857  72.56  0.140 (Allied)  0.150 (BIA)  2.577 (computed, Allied wall)\nIMC (ANSI C80.6)  3  78  3.476  88.29  0.140 (Allied)  0.150 (BIA)  3.196 (computed, Allied wall)\nIMC (ANSI C80.6)  3-1/2  91  3.971  100.86  0.140 (Allied)  0.150 (BIA)  3.691 (computed, Allied wall)\nIMC (ANSI C80.6)  4  103  4.466  113.43  0.140 (Allied)  0.150 (BIA)  4.186 (computed, Allied wall)\nEMT (ANSI C80.3), sizes above the emt-conduit page  2-1/2  63  2.875  73.00  0.072 (BIA)  -  2.731 (computed)\nEMT (ANSI C80.3), sizes above the emt-conduit page  3  78  3.500  88.90  0.072 (BIA)  -  3.356 (computed)\nEMT (ANSI C80.3), sizes above the emt-conduit page  3-1/2  91  4.000  101.60  0.083 (BIA)  -  3.834 (computed)\nEMT (ANSI C80.3), sizes above the emt-conduit page  4  103  4.500  114.30  0.083 (BIA)  -  4.334 (computed)\n\nFiles elsewhere (not hosted by Xem Studio; license as stated by the publisher):\n- Wheatland Tube: Rigid Metal Conduit submittal sheet (Canada, English): nominal OD and ID by trade size 1/2 to 6, ANSI C80.1, UL 6 — web — Publisher's page; dimensions are facts — https://www.wheatland.com/wp-content/uploads/2022/05/Rigid-Metal-Conduit-Submittal-Sheet-–-Canada-English.pdf\n- BIA (biaonline.com): Conduit catalog page 7201: GRC (ANSI C80.1), IMC (ANSI C80.6) and EMT (ANSI C80.3) OD, wall by trade size (OD of GRC and IMC printed rounded to 0.1 in) — web — Publisher's page; dimensions are facts — https://www.biaonline.com/catalog/pdfs/72/7201.pdf\n- Allied Tube & Conduit (utilitypipesupply.com copy): IMC cut sheet: OD and wall by trade size 1/2 to 4 (ANSI C80.6, UL 1242) — web — Publisher's page; dimensions are facts — https://utilitypipesupply.com/cdn/shop/files/Allied_Tube_Conduit_IMC_Cut_Sheet.pdf\n- Steel Tube Institute: Steel conduit and EMT metric designators (trade sizes are for identification, not actual dimensions) — web — Publisher's page; dimensions are facts — https://steeltubeinstitute.org/faq/steel-conduit-emt-metric-designators/\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=rigid-imc-emt-conduit-sizes-to-4-in\n",
 "sources": [
  {
   "publisher": "Wheatland Tube",
   "title": "Rigid Metal Conduit submittal sheet (Canada, English): nominal OD and ID by trade size 1/2 to 6, ANSI C80.1, UL 6",
   "url": "https://www.wheatland.com/wp-content/uploads/2022/05/Rigid-Metal-Conduit-Submittal-Sheet-–-Canada-English.pdf",
   "formats": [
    "web"
   ],
   "license": "Publisher's page; dimensions are facts",
   "license_verified": true,
   "hosted": false
  },
  {
   "publisher": "BIA (biaonline.com)",
   "title": "Conduit catalog page 7201: GRC (ANSI C80.1), IMC (ANSI C80.6) and EMT (ANSI C80.3) OD, wall by trade size (OD of GRC and IMC printed rounded to 0.1 in)",
   "url": "https://www.biaonline.com/catalog/pdfs/72/7201.pdf",
   "formats": [
    "web"
   ],
   "license": "Publisher's page; dimensions are facts",
   "license_verified": true,
   "hosted": false
  },
  {
   "publisher": "Allied Tube & Conduit (utilitypipesupply.com copy)",
   "title": "IMC cut sheet: OD and wall by trade size 1/2 to 4 (ANSI C80.6, UL 1242)",
   "url": "https://utilitypipesupply.com/cdn/shop/files/Allied_Tube_Conduit_IMC_Cut_Sheet.pdf",
   "formats": [
    "web"
   ],
   "license": "Publisher's page; dimensions are facts",
   "license_verified": true,
   "hosted": false
  },
  {
   "publisher": "Steel Tube Institute",
   "title": "Steel conduit and EMT metric designators (trade sizes are for identification, not actual dimensions)",
   "url": "https://steeltubeinstitute.org/faq/steel-conduit-emt-metric-designators/",
   "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": [
  "emt-conduit",
  "conduit-knockout-diameters-nema-bulletin-71",
  "schedule-40-pipe",
  "device-boxes-us",
  "metal-boxes-us",
  "strut-channel-1-5-8",
  "t-slot-outlet-raceway"
 ],
 "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": "rigid conduit OD",
   "exact": "1/2: 21.34, 3/4: 26.67, 1: 33.40, 2: 60.33",
   "mates": "knockout of the same trade size (Ø22.225, Ø28.17, Ø34.925, Ø62.71 nominal)",
   "fit": "designed",
   "files": "all"
  },
  {
   "feature": "IMC OD",
   "exact": "1/2: 20.70, 3/4: 26.13, 1: 32.76",
   "mates": "knockout of the same trade size",
   "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 OD of 1/2 inch rigid conduit?",
   "a": "0.840 in (21.34 mm), 0.104 in wall, 0.632 in ID (Wheatland); the same OD as NPS 1/2 pipe."
  },
  {
   "q": "What is the OD of 3/4 inch IMC?",
   "a": "1.029 in (26.13 mm) per Allied Tube; wall 0.075 in (Allied) or 0.083 in (BIA)."
  },
  {
   "q": "What is the OD of 3 inch EMT?",
   "a": "3.500 in (88.9 mm), 0.072 in wall (BIA)."
  },
  {
   "q": "What does metric designator 21 mean?",
   "a": "It identifies 3/4 in trade size (identification only, not a dimension)."
  }
 ],
 "files_license": null,
 "offers": [],
 "markdown": "https://xemstudio.com/objects/rigid-imc-emt-conduit-sizes-to-4-in/index.md"
}