3 Gallon Carboy Dimensions?

Hello all,

I've done a handful of extract brews, and I've decided to start doing smaller 2.5 gallon batches for a number of reasons, including wanting to do a full boil on an electric stove, and being able to brew more often.

My question is, does anyone know the dimensions of a 3 gallon carboy? I'd like to be able to put it inside of the big cooler I have for fermenting without having to modify it. Being a student, I need a cheap quick and low tech way to control fermentation temps, and using a cooler my parents already own seemed like a good idea. Thanks in advance.

I've got two here. I measured the box, so there is a tiny bit of wiggle room.

9.5" square (Diameter ever so slightly less) , 17 inches high. Plus 6 inches for the airlock.

Are you talking about the 3 gallon glass carboys, plastic water bottles or 3 gallon better bottles?



The better bottles are square.. I have seen and used two different sized 3 gallon water jugs for small batch fermentations, one brand is short and squat, and looks like a traditional 5 gallon better bottle/water bottle only squat, and the other is tall and narrow.....

I am at work, so I can't measure them...sorry.

Thanks guys. I think a 3 gallon with an airlock may be a bit close height wise, I'm considering just putting them in three one gallons.

You mean thos style wouldn't work for you?

THey are pretty squat.

Rough measurements of a 3 gallon glass carboy:

9" diameter
12.5" to shoulder
16.75" to top
20.25" to top of inserted 3pc airlock with universal stopper

Remember, you don't NEED to use an airlock, you could go with a blowoff tube instead, or do like what a lot of people are trying and using tinfoil instead of an airlock or blowoff tube.

Revvy said:

Remember, you don't NEED to use an airlock, you could go with a blowoff tube instead, or do like what a lot of people are trying and using tinfoil instead of an airlock or blowoff tube.

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Why wouldn't you use an airlock?

Revvy said:

Remember, you don't NEED to use an airlock, you could go with a blowoff tube instead, or do like what a lot of people are trying and using tinfoil instead of an airlock or blowoff tube.

Click to expand...

That's what I do. I have a 3 gallon better bottle. It is just a bit too tall for my mini-fridge that I use for fermenting, so I just use a small little hose as a blowoff tube and it fits perfectly.

Here's a picture from a 1.5 gallon brew I did a while ago:

(Don't worry, I pushed the tubing into the liquid after taking the picture)

As you can see, an airlock wouldn't fit in there, but with the blowoff tube it fits perfectly.

westernbacon said:

Why wouldn't you use an airlock?

Click to expand...

He couldn't fit in his cabinet.

Remember, an airlock is just a vent, a valve to release excess co2 to keep your beer in your fermenter and not on your ceiling. It's not a magical fermentation gauge. It's a way to let co2 out without letting microbes in. It's not "necessary" for beer to ferment-the yeast doesn't know whether there is an airlock above it or not, it just makes beer and farts c02.....

Some people cover their fermenters with trays or pieces of plexiglass, or put their bucket lids on loosely, or use tinfoil or plastic wrap, or blowoff tubes. Northern Brewer or Midwest supplies just came out with a little rubber bleeder valve thingy that does the same thing on buckets without needing all the superficial plastic.


Holden, that looks great!!!!

Of course for a gallon and a half brew you could get one of those 2-2.5 gallon "montana jars" like this;




From here https://www.homebrewtalk.com/f12/tepache-200053/

And here's info on turning one into a fermenter...


2 1/2 gallon Montana Jar Fermenter

Of course the metal lid in the one from the thread (from target) is important for making an airlock grommet space. Can't easily do it with a glass top.

cool that makes sense, he just needed something shorter

westernbacon said:

cool that makes sense, he just needed something shorter

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Yeah....but a lot of new brewers seem to ascribe more importance to an airlock that it actually has. Many seem to think that if there's no bubbling (or no airlock) then the beer isn't fermenting, despite krausen and drops in gravity. But it's really just something to keep the fermenter from blowing up.

K