Actual volume of 5 gal carboy

What's the actual volume of a 5gal carboy? Is it supposed to be 5gal if you fill it all the way to the top of the opening? Why don't they mold in gallon marks on the sides?

5 gallons is if completely full. Don't know why they don't come marked, but marking is easy to do on your own.

Kilted Brewer said:

5 gallons is if completely full. Don't know why they don't come marked, but marking is easy to do on your own.

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My 5 gallon carboys are 5 gallons at the shoulder. Completely full is about 5.5 gallons. I just know it, so it doesn't matter too much to me any more. It would be nice if they were marked, but it's not a problem that they are not.

If you want to be sure, you could fill it a gallon at a time, marking with masking tape or a permanent marking.

Interesting...Let's take Apfelwein for an example. I purchase 5 gallons, doesn't matter the package size. I can not get all five gallons into the carboy without it being right to the top.

There are apparently multiple sizes of 5g carboys.... weird. Mine are about 5.5g to the top of the bottle, 5g at the shoulder.

Just measured mine. Both are 5 gal just over the shoulder (~1/3 between the shoulder and top riser), and ~5.2 to the top.

It varies - what's so surprising about that? If you think the barrel-banded thin glass things typical at many homebrew shops have much relation to the thick, smooth-walled acid carboys, you've got another think coming. Even among acid carboys, different manufacturers vary somewhat - and whatever the case may be with how few places are still making them, they can last a long time, and have been made by many places.

If you want to graduate the thing, select your precision measuring device of choice and measure in precise amounts of water, then mark the outside with a sharpie.

I have one mark, on both sides of my primary carboy, which simply tells me where one of my secondaries, full, comes to. That lets me know what I'm shooting for. The secondaries in question typically are about 5.25 gallons up into the narrow part of the neck, which is where I like to secondary. If I get the primary a bit over the line to account for trub, I get a full secondary. It's not a rigid rule, as I do full boils, so my primary volume measurement is what's scratched into my kettle spoon - I don't normally add water.

Kilted Brewer said:

Interesting...Let's take Apfelwein for an example. I purchase 5 gallons, doesn't matter the package size. I can not get all five gallons into the carboy without it being right to the top.

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Correct me if i'm wrong, but assuming you add 2 lbs of sugar to your apfelwein, that will displace some volume in your carboy. Not sure if that's the reason 5 gallons of juice doesn't fit, but something to consider.

You could be right...I just transferred a batch of IPA to a keg and did some quick measurements as I was cleaning. 5 gallons appears to be just pass the shoulder.

bytor1100 had a good writeup on marking your carboys with an acid etch