How many gallons are there in a beer barrel?

And a few other answers to questions like ‘how many beers are in keg’?

My beer brewing class was recently given the opportunity to visit a local brewery on one of their brewing days. Myself and the 20 other students that joined got an all access, behind-the-scenes look at what goes in to a brew day at a commercial brewery from start to finish. We were allowed to pepper our gracious brewmaster hosts with as many questions as we had. One student asked what the capacity of the brewhouse is - in other words, how much beer could they make at once. The answer was short and sweet - 15 barrels.

You could hear the oohs and aahs coming from the student’s mouths. I was no different. I did the math quickly in my head and was able to determine that their brewhouse batch size is 465 times larger than my batch size at home. That got me thinking - how many people actually know how many gallons of beer there are in a gallon. How about the number of beers in a keg? Let’s find out, shall we….

How many gallons are there in a barrel of beer?

There are 31 US gallons per full barrel of beer. Why is that? I couldn’t tell you. I did some research and came up empty. Perhaps if I find a beer historian that will be the first question I ask of them. Also note that a barrel of beer will be abbreviated as bbl. The brewery that my class visited produces beer on a 15 barrel system, or 15 bbl.

How many beers are in a standard sized keg?

Another question that I hear all of the time. Let’s first clarify what is a standard size keg. A standard or full size keg is what you’ll find in most restaurants and bars and it’s probably what comes to mind when you think of a beer keg. They are big and made of stainless steel so they are easy to clean and won’t corrode. It’s considered to be the ‘mack daddy’ of portable beer vessels, though with a filled weight of about 161 lbs I’d argue that only a bodybuilder or powerlifter (with a large truck, mind you) would consider an average keg to be portable.

Now that we know how many gallons are in barrel we can easily answer the question about keg size. A standard keg of beer is also known as a half-barrel keg because, you guessed it, it will hold a 1/2 bbl, or 15.5 gallons (half of 31) of beer. As there are 128 ounces in a gallon, that means a standard sized keg will hold 1,984 ounces of beer. That’s equivalent to:

• 124 US pints (16oz) or

• 164 12oz bottles

What are all of the other common types of kegs and how much beer do they hold?

Scaling down from a standard, half barrel size keg, the next size down is a quarter of a barrel keg. These come in two variations - squat and slim, with each holding the same volume of beer - 1/4 bbl, or 7.75 gallons, or 992 oz of beer.

The squat version is also known as a pony keg. It has the same diameter as a half keg, but it’s roughly half its height

The slim version of the quarter barrel keg is just as tall as a half keg but has a much smaller footprint.

If I need to bring some beer to party, I’d rather bring a quarter keg than a half keg. They are way easier to handle and shouldn’t require as large of a keg deposit as its big brother.

The next smaller size is a sixth barrel keg, also known as a sixtel.

This will hold 1/6 bbl, or 5.16 gallons, or 661 oz of beer

Next we have the Cornelius keg (aka Corny Keg) - this will hold 5 gallons, or 640 oz of beer.

Note that a Sixtel and Corny keg have almost the same capacity. The main difference between these two types of kegs comes down to the types of connections used. A corny keg will use either ball lock or pin lock connectors for the carbon dioxide (CO2) gas and beer lines. All of the other types of kegs mentioned above will require a device called a keg coupler instead of ball or pin lock connectors.

Many homebrewing recipes are written for 5 gallon batch sizes thus its not surprising that corny kegs seem to be ubiquitous amongst home brewers, though the other types of kegs are also common because they can easily be hooked up to kegerators.

These 5 gallon size corny kegs are also very popular with craft breweries.

Also popular amongst homebrewers are these torpedo kegs. Torpedo kegs can be found in a few different sizes: 5 gallon, 2 1/2 gallon all the way down to 1 1/2 gallon, which happens to be my preferred size.

Like corny kegs, they use ball lock connectors (pin locks are not available) instead of special keg connectors. Unlike corny kegs, they have no rubber tops or bottoms - just metal. The all metal feature is nice as are the extra tall handles which are designed to allow for easy stacking. I can fit two stacked 1 1/2 gallon kegs in my mini ‘fridge.

I’ve also been able to find these super-slim mini kegs in 1/2 gallon and 1 gallon sizes. These are nice if you’re really tight on space. These aren’t always supplied with a ball lock connector - sometimes they are only supplied with the lid, so just be mindful of that when purchasing.

Though there are a few other ‘oddball’ sizes out there, this pretty much covers most of the standard keg types.

What about non-US measures?

A European keg will typically hold either 20 or 50 liters of beer. 50 liters of beer is equal to about 11 imperial gallons of beer, which also happens to be a standard keg size in the United Kingdom. For reference, an imperial gallon (imp gal for short) is equal to 1.2 U.S. gallons. Another way to say express this would be to say that a standard UK is 25% bigger than a US keg.