{
 "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": "lamp-base-edison-screw",
 "name": "Edison screw lamp bases: E12, E14, E26, E27, E39, E40 thread sizes",
 "kind": "standard",
 "category": "Home & kitchen",
 "group": "Household",
 "year": null,
 "question": "What are the thread diameter and pitch of E26, E27, E14 and E12 light bulb bases?",
 "tags": [
  "light bulb",
  "lamp base",
  "socket",
  "e26",
  "e27",
  "lamp holder",
  "standard"
 ],
 "aliases": [
  "e26 base dimensions",
  "e27 thread diameter",
  "e12 candelabra base size",
  "e26 vs e27",
  "light bulb base sizes",
  "lamp socket adapter dimensions"
 ],
 "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/lamp-base-edison-screw/",
 "sheet_txt": "https://xemstudio.com/objects/lamp-base-edison-screw/sheet.txt",
 "sheet": {
  "basis": "Wikipedia Edison screw table (IEC 60061-1 / ANSI C81.67 values); numbers only",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "notes": [
   "The number after E is the thread outer diameter in mm. E26 is the US medium base, E27 the European one; E12 is the US candelabra, E14 the European small base, E39 the US mogul.",
   "Pitch: E14 2.82 mm (9 threads per inch), E26 7 threads per inch (3.63 mm, computed 25.4 / 7), E27 3.62 mm, E40 6.35 mm. E12 and E39 pitch was not confirmed on a reachable page, so none is given.",
   "No file: the thread profile (flank angle, root and crest radius), base length and gauge shape are not published on any page available to Xem, and a plain cylinder at the major diameter would not be the base."
  ],
  "table": {
   "columns": [
    "base",
    "thread outer diameter, mm",
    "pitch"
   ],
   "rows": [
    [
     "E12 candelabra",
     "12",
     "not confirmed"
    ],
    [
     "E14 small",
     "14",
     "2.82 mm (9 per in)"
    ],
    [
     "E26 medium (US)",
     "26",
     "7 per in = 3.63 mm"
    ],
    [
     "E27 medium",
     "27",
     "3.62 mm"
    ],
    [
     "E39 mogul (US)",
     "39",
     "not confirmed"
    ],
    [
     "E40 goliath",
     "40",
     "6.35 mm"
    ]
   ]
  }
 },
 "sheet_text": "Edison screw lamp bases: E12, E14, E26, E27, E39, E40 thread sizes — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/lamp-base-edison-screw/  (sheet CC BY 4.0)\nBasis: Wikipedia Edison screw table (IEC 60061-1 / ANSI C81.67 values); numbers only\nCatalog version: 2026-10-20\n\nSizes: see table below\n- The number after E is the thread outer diameter in mm. E26 is the US medium base, E27 the European one; E12 is the US candelabra, E14 the European small base, E39 the US mogul.\n- Pitch: E14 2.82 mm (9 threads per inch), E26 7 threads per inch (3.63 mm, computed 25.4 / 7), E27 3.62 mm, E40 6.35 mm. E12 and E39 pitch was not confirmed on a reachable page, so none is given.\n- No file: the thread profile (flank angle, root and crest radius), base length and gauge shape are not published on any page available to Xem, and a plain cylinder at the major diameter would not be the base.\n\nbase  thread outer diameter, mm  pitch\nE12 candelabra  12  not confirmed\nE14 small  14  2.82 mm (9 per in)\nE26 medium (US)  26  7 per in = 3.63 mm\nE27 medium  27  3.62 mm\nE39 mogul (US)  39  not confirmed\nE40 goliath  40  6.35 mm\n\nFiles elsewhere (not hosted by Xem Studio; license as stated by the publisher):\n- Wikipedia: Edison screw — web — CC BY-SA; facts only — https://en.wikipedia.org/wiki/Edison_screw\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=lamp-base-edison-screw\n",
 "sources": [
  {
   "publisher": "Wikipedia",
   "title": "Edison screw",
   "url": "https://en.wikipedia.org/wiki/Edison_screw",
   "formats": [
    "web"
   ],
   "license": "CC BY-SA; facts 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": [
  "a19-light-bulb",
  "a21-light-bulb",
  "br30-light-bulb",
  "br40-light-bulb",
  "par30l-light-bulb",
  "par38-light-bulb",
  "g25-light-bulb",
  "mr16-light-bulb",
  "gu10-par16-light-bulb",
  "lamp-base-gu10-gu5-3"
 ],
 "fits": [],
 "dimensions": "exact (nominal, no printing tolerance)",
 "dimension_rule": "All geometry on Xem Studio is exact (nominal, true size) with no printing tolerance. 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.",
 "mating": [],
 "faq": [
  {
   "q": "What is the diameter of an E26 base?",
   "a": "26 mm thread outer diameter, 7 threads per inch."
  },
  {
   "q": "Is E26 the same as E27?",
   "a": "No: 26 mm and 27 mm; they often screw in but are different standards."
  }
 ],
 "files_license": null,
 "offers": [],
 "markdown": "https://xemstudio.com/objects/lamp-base-edison-screw/index.md"
}