How big is my carboy?

Ok, I bought it used for $15 bucks from a friend. He says its 6.5 gallons. After pouring a batch in that I figured was about 5 gallons it could even hold it all. So my question is this... I either made 7 gallons of beer or my fermenter is 5 gallons. My height is 19" and the carboy is 33.5 " around. Is it a 5 or a 6.5? Can anyone help?

how about using a known measure to find capacity. either a 1 gallon milk jug, or 1/2 gallon-1 gallon pitcher.

I think he's wanting to find out now, without pouring out the precious beer he has in it at the moment.

oops i kinda purged the fact he had beer in it.

ChshreCat said:

I think he's wanting to find out now. . .

Click to expand...

Some quick measurements:

5 gallon = 33 1/2" circumference x 19" tall
6 gallon = 36" circumference x 20" tall
6 1/2 gallon = 38" circumference x 21" tall

Area = R x R x 3.14
Gallons = area x average depth x 7.48
Liters = Gallons x 3.785
OR
Gals. = Diameter x Diameter x Avg. Depth x 5.9

based on circum of 33.5
radius = 5.32 inches = .44333 feet

.44333 x .44333 x 3.14 = 0.61714 area
0.61714 x 1.375 (16.5") x 7.47 = 6.338 gallons

i would assume it is 6.5 gallons, this doesnt account for the glass thickness, so it may be a 6 gallon carboy

I got all kinds of different answers when i googled . Above AnOld UR says its a 5 gallon and Pure you believe its 6.5 or 6. I guess I may have to wait til after fermentation to fill it with water using a milk gallon. I REALLY hope its 6.5. Its made in Mexico and has the checkered look to the glass, not smooth all the way around... has the bumps in the glass if that helps at all.

depending on the age it could be any size. is it stamped anywhere?

It's almost certainly a 5 gallon carboy.

ok never try to tip your carboy to look for stamps without holding the blow off cup full of yeasty beer blowoff... especially on a rug. All i saw was do not bump, do not heat and fragile made in mexico. And Cat22 yes I am fearing it is 5 too... pretty bummed. It looks big enough to hold 6.5 to me though... when I think of pouring gallons of milk in it seems like 5 wouldn't reach the top but who knows. Now to clean my rug.