{
 "version": "2026-10-20",
 "license": "Dimension sheets are written by Xem Studio from the cited sources and are free to use (CC BY 4.0, attribute 'Xem Studio'). Linked files belong to their publishers under the license shown; Xem Studio does not host them. 'license_verified: false' means the license shown is from memory or the publisher's page as last read and should be confirmed at the link before commercial use.",
 "slug": "pet-bottle-necks-pco1881",
 "name": "PET bottle necks: PCO 1881 (soda, 28 mm) and 38 mm (milk/juice)",
 "kind": "standard",
 "category": "Hardware",
 "group": "Found & household materials",
 "year": null,
 "question": "What is the thread size of a soda bottle cap?",
 "tags": [
  "bottle",
  "pet",
  "cap",
  "thread",
  "pco1881",
  "stirling",
  "long earth society",
  "found materials"
 ],
 "aliases": [
  "soda bottle thread size",
  "pco 1881 dimensions",
  "bottle cap thread 28mm",
  "3d print bottle cap",
  "water bottle neck size",
  "2 liter bottle dimensions"
 ],
 "overall_mm": {
  "length": null,
  "width": null,
  "height": null
 },
 "official_cad": false,
 "xem_status": "free-files",
 "les": true,
 "free_files": 0,
 "url": "https://xemstudio.com/objects/pet-bottle-necks-pco1881/",
 "sheet_txt": "https://xemstudio.com/objects/pet-bottle-necks-pco1881/sheet.txt",
 "sheet": {
  "basis": "PCO 1881 (ISBT) neck finish; 38 mm three-start finish per ISBT; bottle body sizes typical",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "notes": [
   "Soda / water bottle neck (PCO 1881): thread OD 27.43 mm, thread root 24.94 mm, 2 mm pitch single-start with 3 thread turns, neck height 17 mm from the support ring to the top, support ring Ø33 mm. Cap ID 28 mm. The older PCO 1810 is 21 mm tall with the same thread.",
   "Milk / juice bottles: 38 mm finish (thread OD 37.5 mm, 3-start, 1.8 mm pitch, 10 mm tall). Water-cooler jugs are 55 mm.",
   "Bottle bodies: 500 mL Ø65 × 200 mm; 1 L Ø80 × 270; 2 L Ø110 × 310, PET wall 0.3 mm. A printed PCO 1881 cap (thread modeled as a 27.9 mm bore with a 2 mm pitch groove) screws onto any soda bottle: pressure vessel to ~8 bar, the clear cylinder of a water-rocket or a pressure test rig. Never heat PET above 70 °C."
  ],
  "table": {
   "columns": [
    "finish",
    "thread_od_mm",
    "root_mm",
    "pitch_mm",
    "height_mm",
    "cap_id_mm"
   ],
   "rows": [
    [
     "PCO 1881 (soda, 28 mm)",
     27.43,
     24.94,
     2,
     17,
     28
    ],
    [
     "PCO 1810 (older 28 mm)",
     27.43,
     24.94,
     2,
     21,
     28
    ],
    [
     "38 mm 3-start (milk/juice)",
     37.5,
     34,
     1.8,
     10,
     38
    ]
   ]
  }
 },
 "sheet_text": "PET bottle necks: PCO 1881 (soda, 28 mm) and 38 mm (milk/juice) — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/pet-bottle-necks-pco1881/  (CC BY 4.0)\nBasis: PCO 1881 (ISBT) neck finish; 38 mm three-start finish per ISBT; bottle body sizes typical\nCatalog version: 2026-10-20\n\nSizes: see table below\n- Soda / water bottle neck (PCO 1881): thread OD 27.43 mm, thread root 24.94 mm, 2 mm pitch single-start with 3 thread turns, neck height 17 mm from the support ring to the top, support ring Ø33 mm. Cap ID 28 mm. The older PCO 1810 is 21 mm tall with the same thread.\n- Milk / juice bottles: 38 mm finish (thread OD 37.5 mm, 3-start, 1.8 mm pitch, 10 mm tall). Water-cooler jugs are 55 mm.\n- Bottle bodies: 500 mL Ø65 × 200 mm; 1 L Ø80 × 270; 2 L Ø110 × 310, PET wall 0.3 mm. A printed PCO 1881 cap (thread modeled as a 27.9 mm bore with a 2 mm pitch groove) screws onto any soda bottle: pressure vessel to ~8 bar, the clear cylinder of a water-rocket or a pressure test rig. Never heat PET above 70 °C.\n\nfinish  thread_od_mm  root_mm  pitch_mm  height_mm  cap_id_mm\nPCO 1881 (soda, 28 mm)  27.43  24.94  2.0  17.0  28.0\nPCO 1810 (older 28 mm)  27.43  24.94  2.0  21.0  28.0\n38 mm 3-start (milk/juice)  37.5  34.0  1.8  10.0  38.0\n\nFiles elsewhere (not hosted by Xem Studio; license as stated by the publisher):\n- Wikipedia: Plastic bottle — web — CC BY-SA 4.0 (text) — https://en.wikipedia.org/wiki/Plastic_bottle\n- ISBT: PCO 1881 finish drawing (International Society of Beverage Technologists) — PDF — ISBT publication [verify license at link] — https://www.threadspecs.com/\n- Long Earth Society: Engine builds (videos and write-ups) — web, video — LES site — https://longearthsociety.com/engineering/\n\nXem Studio scan: not needed; this is a published standard. The sheet is the geometry.\nAPI: https://xemstudio.com/api/geometry?object=pet-bottle-necks-pco1881\n",
 "sources": [
  {
   "publisher": "Wikipedia",
   "title": "Plastic bottle",
   "url": "https://en.wikipedia.org/wiki/Plastic_bottle",
   "formats": [
    "web"
   ],
   "license": "CC BY-SA 4.0 (text)",
   "license_verified": true,
   "hosted": false
  },
  {
   "publisher": "ISBT",
   "title": "PCO 1881 finish drawing (International Society of Beverage Technologists)",
   "url": "https://www.threadspecs.com/",
   "formats": [
    "PDF"
   ],
   "license": "ISBT publication",
   "license_verified": false,
   "hosted": false
  },
  {
   "publisher": "Long Earth Society",
   "title": "Engine builds (videos and write-ups)",
   "url": "https://longearthsociety.com/engineering/",
   "formats": [
    "web",
    "video"
   ],
   "license": "LES site",
   "license_verified": true,
   "hosted": false
  }
 ],
 "xem": {
  "status": "free-files",
  "sheet_free": true,
  "mesh_price_usd": null,
  "step_price_usd": null,
  "tolerance_mm": null
 },
 "related": [
  "mason-jars-and-lids",
  "rubber-stoppers-and-corks",
  "o-rings-metric",
  "can-engine-printed-kit"
 ],
 "faq": [
  {
   "q": "What is the thread size on a soda bottle?",
   "a": "PCO 1881: 27.43 mm thread OD, 2 mm pitch, 17 mm tall neck; caps are 28 mm. All standard soda and water bottles use it."
  },
  {
   "q": "Can I 3D print a cap for a soda bottle?",
   "a": "Yes: a 27.9 mm bore with a 2 mm pitch, 1.2 mm deep groove, 3 turns; print at 0.12 mm layers and it seals with a 1 mm silicone disc."
  }
 ],
 "files_license": null,
 "offers": [],
 "markdown": "https://xemstudio.com/objects/pet-bottle-necks-pco1881/index.md"
}