{
 "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": "rubber-stoppers",
 "name": "Laboratory rubber stoppers #0–#13 (25 mm tall)",
 "kind": "standard",
 "category": "Hardware",
 "group": "Found & household materials",
 "year": null,
 "question": "What size rubber stopper fits a 25 mm test tube or a soda bottle?",
 "tags": [
  "stopper",
  "bung",
  "seal",
  "lab",
  "found materials",
  "stirling",
  "long earth society"
 ],
 "aliases": [
  "rubber stopper sizes",
  "stopper size chart",
  "#6 stopper dimensions",
  "test tube stopper size",
  "bung sizes"
 ],
 "overall_mm": {
  "length": null,
  "width": null,
  "height": null
 },
 "official_cad": false,
 "xem_status": "free-files",
 "les": true,
 "free_files": 16,
 "url": "https://xemstudio.com/objects/rubber-stoppers/",
 "sheet_txt": "https://xemstudio.com/objects/rubber-stoppers/sheet.txt",
 "sheet": {
  "basis": "Standard US laboratory stopper sizes: top and bottom diameters, 25 mm tall; drawn as a straight taper (loft) between them",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "notes": [
   "Stopper number → top / bottom diameter (mm): #0 17/13, #1 19/15, #2 20/16, #3 24/18, #4 26/20, #5 27/23, #6 32/26, #6½ 34/27, #7 37/30, #8 41/33, #9 45/37, #10 50/42, #11 56/48, #12 64/54, #13 68/58; all 25 mm tall.",
   "Each file is a solid truncated cone between those diameters; one- and two-hole versions of the real stoppers take 5–7 mm tube.",
   "Pick the stopper whose mid-diameter is about 1 mm over the opening: 16 mm test tube #0, 20 mm #2, 25 mm #4/#5, 28 mm soda-bottle neck #6.",
   "The table gives the opening range each number seals.",
   "One file is a #4 bored through on its axis at Ø4 (stopper-4-bore-4): the stopper of the test-tube marble engine, with a 4 mm OD brass tube through it. The bore is my geometry, drawn at the tube's OD."
  ],
  "table": {
   "columns": [
    "number",
    "top_mm",
    "bottom_mm",
    "height_mm",
    "fits_opening_mm"
   ],
   "rows": [
    [
     "#0",
     17,
     13,
     25,
     "14–16"
    ],
    [
     "#1",
     19,
     15,
     25,
     "16–18"
    ],
    [
     "#2",
     20,
     16,
     25,
     "17–19"
    ],
    [
     "#3",
     24,
     18,
     25,
     "19–23"
    ],
    [
     "#4",
     26,
     20,
     25,
     "21–25"
    ],
    [
     "#5",
     27,
     23,
     25,
     "24–26"
    ],
    [
     "#6",
     32,
     26,
     25,
     "27–31"
    ],
    [
     "#6.5",
     34,
     27,
     25,
     "28–33"
    ],
    [
     "#7",
     37,
     30,
     25,
     "31–36"
    ],
    [
     "#8",
     41,
     33,
     25,
     "34–40"
    ],
    [
     "#9",
     45,
     37,
     25,
     "38–44"
    ],
    [
     "#10",
     50,
     42,
     25,
     "43–49"
    ],
    [
     "#11",
     56,
     48,
     25,
     "49–55"
    ],
    [
     "#12",
     64,
     54,
     25,
     "55–63"
    ],
    [
     "#13",
     68,
     58,
     25,
     "59–67"
    ]
   ]
  }
 },
 "sheet_text": "Laboratory rubber stoppers #0–#13 (25 mm tall) — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/rubber-stoppers/  (CC BY 4.0)\nBasis: Standard US laboratory stopper sizes: top and bottom diameters, 25 mm tall; drawn as a straight taper (loft) between them\nCatalog version: 2026-10-20\n\nSizes: see table below\n- Stopper number → top / bottom diameter (mm): #0 17/13, #1 19/15, #2 20/16, #3 24/18, #4 26/20, #5 27/23, #6 32/26, #6½ 34/27, #7 37/30, #8 41/33, #9 45/37, #10 50/42, #11 56/48, #12 64/54, #13 68/58; all 25 mm tall.\n- Each file is a solid truncated cone between those diameters; one- and two-hole versions of the real stoppers take 5–7 mm tube.\n- Pick the stopper whose mid-diameter is about 1 mm over the opening: 16 mm test tube #0, 20 mm #2, 25 mm #4/#5, 28 mm soda-bottle neck #6.\n- The table gives the opening range each number seals.\n- One file is a #4 bored through on its axis at Ø4 (stopper-4-bore-4): the stopper of the test-tube marble engine, with a 4 mm OD brass tube through it. The bore is my geometry, drawn at the tube's OD.\n\nnumber  top_mm  bottom_mm  height_mm  fits_opening_mm\n#0  17  13  25  14–16\n#1  19  15  25  16–18\n#2  20  16  25  17–19\n#3  24  18  25  19–23\n#4  26  20  25  21–25\n#5  27  23  25  24–26\n#6  32  26  25  27–31\n#6.5  34  27  25  28–33\n#7  37  30  25  31–36\n#8  41  33  25  34–40\n#9  45  37  25  38–44\n#10  50  42  25  43–49\n#11  56  48  25  49–55\n#12  64  54  25  55–63\n#13  68  58  25  59–67\n\nFiles elsewhere (not hosted by Xem Studio; license as stated by the publisher):\n- Wikipedia: Bung — web — CC BY-SA 4.0 (text) — https://en.wikipedia.org/wiki/Bung\n- Wikipedia: Cork (material) — web — CC BY-SA 4.0 (text) — https://en.wikipedia.org/wiki/Cork_(material)\n- Long Earth Society: Engine builds (videos and write-ups) — web, video — LES site — https://longearthsociety.com/engineering/\n\nFree files (CC BY 4.0, Xem Studio; STEP + STL, 16 parts): https://xemstudio.com/files/hardware/rubber-stoppers/index.json\nAPI: https://xemstudio.com/api/geometry?object=rubber-stoppers\n",
 "sources": [
  {
   "publisher": "Wikipedia",
   "title": "Bung",
   "url": "https://en.wikipedia.org/wiki/Bung",
   "formats": [
    "web"
   ],
   "license": "CC BY-SA 4.0 (text)",
   "license_verified": true,
   "hosted": false
  },
  {
   "publisher": "Wikipedia",
   "title": "Cork (material)",
   "url": "https://en.wikipedia.org/wiki/Cork_(material)",
   "formats": [
    "web"
   ],
   "license": "CC BY-SA 4.0 (text)",
   "license_verified": true,
   "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": [
  "wine-corks",
  "borosilicate-test-tubes",
  "pet-bottle-necks-pco1881",
  "mason-jar-lid",
  "list-test-tube-marble-engine",
  "brass-tube-ks"
 ],
 "fits": [
  {
   "role": "Goes in or on",
   "items": [
    {
     "slug": "borosilicate-test-tubes",
     "why": "stopper closes the tube mouth"
    },
    {
     "slug": "pet-bottle-necks-pco1881",
     "why": "#6 in the 28 mm neck"
    }
   ]
  },
  {
   "role": "Alternatives",
   "items": [
    {
     "slug": "wine-corks",
     "why": "a parallel Ø24 cork for a 22–23 mm opening"
    }
   ]
  }
 ],
 "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": [
  {
   "feature": "axial bore",
   "exact": "Ø4",
   "mates": "brass-4mm tube OD",
   "fit": "press",
   "files": "stopper-4-bore-4"
  },
  {
   "feature": "taper in a tube mouth",
   "exact": "#4: Ø22.6 line 10.83 above the small end",
   "mates": "25 × 150 test tube bore Ø22.6",
   "fit": "press",
   "files": "stopper-4-bore-4"
  }
 ],
 "fit_classes": {
  "press": "stays put: pin, tube, bearing or magnet held by interference. Typical FDM: hole +0.0 to +0.1 mm on diameter.",
  "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. Typical FDM: +0.2 mm.",
  "run": "turns or slides in use: pin in a link, rod through a guide. Typical FDM: +0.3 mm.",
  "socket": "large sliding fit: syringe barrel, sleeve, bobbin in a bore. Typical FDM: +0.3 mm.",
  "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 rubber stopper fits a 20 mm test tube?",
   "a": "#2 (20 mm top, 16 mm bottom); #1 for 16–18 mm tubes, #4 for a 25 mm tube."
  },
  {
   "q": "Which stopper fits a soda bottle neck?",
   "a": "#6 (32/26 mm) for the 28 mm PCO 1881 neck; #7 for a 38 mm neck."
  },
  {
   "q": "How tall is a lab rubber stopper?",
   "a": "25 mm for every size from #0 to #13."
  }
 ],
 "files_license": null,
 "offers": [
  {
   "file": "stopper-0",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/rubber-stoppers-and-corks/stopper-0.step",
   "stl": "https://xemstudio.com/files/hardware/rubber-stoppers-and-corks/stopper-0.stl",
   "note": "#0 stopper: Ø17 top, Ø13 bottom, 25 mm tall"
  },
  {
   "file": "stopper-1",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/rubber-stoppers-and-corks/stopper-1.step",
   "stl": "https://xemstudio.com/files/hardware/rubber-stoppers-and-corks/stopper-1.stl",
   "note": "#1 stopper: Ø19 top, Ø15 bottom, 25 mm tall"
  },
  {
   "file": "stopper-2",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/rubber-stoppers-and-corks/stopper-2.step",
   "stl": "https://xemstudio.com/files/hardware/rubber-stoppers-and-corks/stopper-2.stl",
   "note": "#2 stopper: Ø20 top, Ø16 bottom, 25 mm tall"
  },
  {
   "file": "stopper-3",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/rubber-stoppers-and-corks/stopper-3.step",
   "stl": "https://xemstudio.com/files/hardware/rubber-stoppers-and-corks/stopper-3.stl",
   "note": "#3 stopper: Ø24 top, Ø18 bottom, 25 mm tall"
  },
  {
   "file": "stopper-4",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/rubber-stoppers-and-corks/stopper-4.step",
   "stl": "https://xemstudio.com/files/hardware/rubber-stoppers-and-corks/stopper-4.stl",
   "note": "#4 stopper: Ø26 top, Ø20 bottom, 25 mm tall"
  },
  {
   "file": "stopper-5",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/rubber-stoppers-and-corks/stopper-5.step",
   "stl": "https://xemstudio.com/files/hardware/rubber-stoppers-and-corks/stopper-5.stl",
   "note": "#5 stopper: Ø27 top, Ø23 bottom, 25 mm tall"
  },
  {
   "file": "stopper-6",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/rubber-stoppers-and-corks/stopper-6.step",
   "stl": "https://xemstudio.com/files/hardware/rubber-stoppers-and-corks/stopper-6.stl",
   "note": "#6 stopper: Ø32 top, Ø26 bottom, 25 mm tall"
  },
  {
   "file": "stopper-6-5",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/rubber-stoppers-and-corks/stopper-6-5.step",
   "stl": "https://xemstudio.com/files/hardware/rubber-stoppers-and-corks/stopper-6-5.stl",
   "note": "#6.5 stopper: Ø34 top, Ø27 bottom, 25 mm tall"
  },
  {
   "file": "stopper-7",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/rubber-stoppers-and-corks/stopper-7.step",
   "stl": "https://xemstudio.com/files/hardware/rubber-stoppers-and-corks/stopper-7.stl",
   "note": "#7 stopper: Ø37 top, Ø30 bottom, 25 mm tall"
  },
  {
   "file": "stopper-8",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/rubber-stoppers-and-corks/stopper-8.step",
   "stl": "https://xemstudio.com/files/hardware/rubber-stoppers-and-corks/stopper-8.stl",
   "note": "#8 stopper: Ø41 top, Ø33 bottom, 25 mm tall"
  },
  {
   "file": "stopper-9",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/rubber-stoppers-and-corks/stopper-9.step",
   "stl": "https://xemstudio.com/files/hardware/rubber-stoppers-and-corks/stopper-9.stl",
   "note": "#9 stopper: Ø45 top, Ø37 bottom, 25 mm tall"
  },
  {
   "file": "stopper-10",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/rubber-stoppers-and-corks/stopper-10.step",
   "stl": "https://xemstudio.com/files/hardware/rubber-stoppers-and-corks/stopper-10.stl",
   "note": "#10 stopper: Ø50 top, Ø42 bottom, 25 mm tall"
  },
  {
   "file": "stopper-11",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/rubber-stoppers-and-corks/stopper-11.step",
   "stl": "https://xemstudio.com/files/hardware/rubber-stoppers-and-corks/stopper-11.stl",
   "note": "#11 stopper: Ø56 top, Ø48 bottom, 25 mm tall"
  },
  {
   "file": "stopper-12",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/rubber-stoppers-and-corks/stopper-12.step",
   "stl": "https://xemstudio.com/files/hardware/rubber-stoppers-and-corks/stopper-12.stl",
   "note": "#12 stopper: Ø64 top, Ø54 bottom, 25 mm tall"
  },
  {
   "file": "stopper-13",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/rubber-stoppers-and-corks/stopper-13.step",
   "stl": "https://xemstudio.com/files/hardware/rubber-stoppers-and-corks/stopper-13.stl",
   "note": "#13 stopper: Ø68 top, Ø58 bottom, 25 mm tall"
  },
  {
   "file": "stopper-4-bore-4",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/rubber-stoppers-and-corks/stopper-4-bore-4.step",
   "stl": "https://xemstudio.com/files/hardware/rubber-stoppers-and-corks/stopper-4-bore-4.stl",
   "note": "#4 stopper (Ø26 top, Ø20 bottom, 25 tall) bored Ø4 on its axis for a 4 mm OD tube (the bore is my geometry, at the tube's OD)"
  }
 ],
 "markdown": "https://xemstudio.com/objects/rubber-stoppers/index.md"
}