What Size Rubber Stopper Fits What?

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Rubber Stopper That Is The Right SizeOne of things that almost every home winemaker uses is a rubber stopper. It’s used to attach an airlock to a plastic fermenter or wine carboy. The rubber stopper is tapered in shape, has a whole in it for the airlock, and comes in various sizes.
Knowing what size of rubber stopper to purchase can be of some issue. Whether you are using a gallon glass carboy or plastic fermenter makes a difference as to the size rubber stopper you need. I thought it would be nice to go over, “what size rubber stopper fits what”, since we offer 25 different sizes to choose from.
I should start of by saying that any bucket fermenter we offer takes a size #2 rubber stopper. This may not be the case with a fermenter purchased elsewhere. It depends on the size of whole the supplier decides to put into the plastic fermenter.
Glass carboys come in an array of sizes and take a different sized rubber stopper as the size changes. There are 6.5 , 6 , 5 and 3 gallon sizes. The rubber stopper size for each is as follows:
6.5 Gal. Glass Carboys (Size #6.5) Shop Carboys
6.0 Gal. Glass Carboys (Size #6.5)
5.0 Gal. Glass Carboys (Size #7)
3.0 Gal. Glass Carboys (Size #7)
7.0 Gal. Large-Mouth (Size #10)
6.0 Gal. Large-Mouth (Size #10)
You may need to size a plastic wine carboy with a rubber stopper as these have become more popular over time. A plastic carboy takes a size #10.0 rubber stopper regardless of its size.
Other sizes of rubber stopper you may need to know is are:
Wine Bottle Opening (Size #2.0)
Beer Bottle Opening (Size #2.0)
Large-Mouth Gallon Glass Jugs, Quick Quarter Turn Lid (Size #8.0)
Small-Mouth Gallon Glass Jugs, Thread-Down Lid (Size #6.0) Shop Wine Airlocks
Visit our website. It lists all of these rubber stoppers and more along with their dimensions.
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Ed Kraus is a 3rd generation home brewer/winemaker and has been an owner of E. C. Kraus since 1999. He has been helping individuals make better wine and beer for over 25 years.

30 thoughts on “What Size Rubber Stopper Fits What?”

    • K, since not all 1/2 gallon growlers may not have the same sized opening, the best way to determine what size stopper you need is to measure the inside diameter of the opening. Then you would choose a rubber stopper that has a bottom diameter that is just slightly smaller.

  2. Chris, you are correct. The 1 inch opening takes a size #6 rubber stopper. The size #8 is for large-mouth gallon jugs. The large-mouth can be recognized by the fact that they have a quarter-turn, quick-locking lid.

  4. Hi!…Just wondering what the size of rubber stopper or cork would be for old 5 gallon bottles that measure 1 1/4 inch at the opening. Thanks
    John

  5. John, It should be a size 6-1/2 rubber stopper. This is based on the measurement you provided.

  6. I purchased a number 8 stopper so I am assuming that I was wrong and it is actually a small have an opening of exactly 1 inch across across. I have an opening of exactly 1 inch across. Is that a number 6 stopper?

  7. What size stopper would fit a regular gallon plastic milk jug?
    I have been drilling a hold in the lid and using silicone to seal an airlock on top, but I would much rather use a rubber stopper.

  9. What size stopper would be used on a 64 fl oz Welch’s grape juice bottle? It’s a fairly large opening so I’m unsure. Thanks!

  10. I am looking for a cork or stopper for a big mouth jar about 6 1/2" wide. Which size do you recommend?

  11. Ed, we do not have any size cork or rubber stopper that large. I’m not sure one is made the big.

    • Julie, I am sorry we do not know what size stopper will fit your antique gallon glass jug. To find out what size stopper you need, measure the inside diameter of the opening and then choose a stopper with a bottom diameter that is slightly smaller.

    • Tammy, I am sorry, we do not know what size stopper you need for your mason jar. But here is how you can determine that yourself. All you need to do is measure the inside diameter of the opening and then choose a rubber stopper with a bottom diameter that is just slightly smaller than the opening. Below is the link to all of the rubber stopper sizes that we carry. You will see that we also carry rubber caps that fit over the outside of the opening.
      Rubber Stoppers
      http://www.eckraus.com/wine-stoppers-caps

    • Neema, to know what size stopper you need, you will measure the inside diameter of opening and then choose a rubber stopper that has a bottom diameter that is just slightly smaller than the opening.

    • Gary, the only way to know for sure what size stopper your need is to measure the inside diameter of the opening and choose a rubber stopper that has a bottom diameter that is just slightly smaller that the opening.

  16. so what you are saying is that you do not know the measurement of all bottle openings and that we the customers must measure our own bottle openings? Well, I’m just too lazy for that, lol

    • Whitney, if the inside diameter of the opening is 5/8″, the size #1 should work fine.

    • Rusty, if the inside diameter of the opening is 1 3/4 inch, he stopper that you want is the #10 that has a bottom diameter of 1 11/16.

    • Rusty, if the inside diameter of the opening is 1 3/4 inch, the #7 stopper has a bottom diameter of 1 3/16 and this would be too small. The stopper that you want for a opening of 1 3/4 is the #10 that has a bottom diameter of 1 11/16.

  20. Thank for sharing this interesting article. I will go to the web page you wrote, to get the lists all of these rubber stoppers and more along with their dimensions.

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