What Size CO2 Tank Does a Kegerator Need?

The 5 lb answer, and the one number nobody publishes

Buy the 5 lb. That's the honest answer to kegerator co2 tank size for most home setups, and the reason has almost nothing to do with how much beer it pours. A 5 lb aluminum cylinder measures roughly 5.25 inches across and 17.5 inches tall, by BeverageCraft's chart, which is small enough that it is often the size chosen to sit inside a cabinet next to a keg. The 10 lb goes to about 6.875 by 20 inches. The 20 lb is 8 inches wide and 27.5 tall, and at that point it lives on the floor beside the unit whether you planned for that or not.

Here's where the standard advice falls apart. Every buying guide leads with kegs per tank, and the published numbers are all over the place — Kegco says its 5 lb tank is good for 5 to 7 kegs, Beverage Factory says 2 to 4 full-size kegs, and BeverageCraft's chart says 15 to 22 five-gallon kegs. Same weight of gas. That spread isn't sloppiness so much as a sign that yield isn't a property of the cylinder at all. The sources themselves point to keg size, serving pressure and temperature, and the gas spent on purging and carbonating before a drop reaches the glass, though none reconciles the figures or shows the arithmetic.

So treat it as a fit problem instead. Measure the cabinet, decide how often you'll drive to the fill shop, and let the tank follow from those two numbers.

Product	Product Dimensions	Item Weight	Choose if you need
GANCOWISE New 5lb	5.24 x 5.24 x 18.27 inches	8.48 pounds	Best all-round size
GANCOWISE New 10lb	20.67 x 6.87 x 20.67 inches	15.69 pounds	Best step up in capacity
GANCOWISE New 20lb	8 x 8 x 27.36 inches	28.4 pounds	Best for heavy use
wzson Paintball	—	—	Best ultra-portable
Kegco 3PB5-RED	—	—	Best looking tank
Homebrew	28 x 6 x 6 inches	15 pounds	Best conversion kit
VEVOR Beer Kegerator	‎21.7 x 20.7 x 33.2 inches	‎97 pounds	Best starter kegerator
VEVOR Beer Kegerator	‎23.7 x 29.1 x 52.4 inches	‎88.2 pounds	Best dual-tap setup
Happybuy	‎21.7 x 20.7 x 33.2 inches	—	Best complete package
Star Sales USA	—	—	Best plain replacement

Measurements come from the manufacturers. The “Choose if you need” call is ours.

Start here

Kegco 3PB5-RED, best for a kegerator that lives out in the open, where the tank is visible and a coloured finish matters as much as the capacity.

For everyone else:

• For the default kegerator gas bottle for anyone tapping a sixth or quarter barrel at home, where a 5 lb aluminum cylinder fits inside or beside most cabinets: GANCOWISE New 5lb.
• For the reader who wants far fewer refill runs but still needs the tank to sit on the floor beside a standard-height kegerator: GANCOWISE New 10lb.
• For someone running a keg through a party pump-free system regularly, or serving multiple taps, who has floor space next to the unit and wants the longest possible interval between fills: GANCOWISE New 20lb.

Know this about the Kegco 3PB5-RED first: listing capacity field reads 5 liters rather than the 5 lb fill weight, so confirm size before ordering

Why four sources give a 5 lb tank four different keg counts

Four published sources give a 5 lb CO2 tank four different keg counts, and the spread is wider than any measurement error could explain. Kegco advertises its own 5 lb aluminum tank as good for 5 to 7 kegs. BeverageCraft's chart says 15 to 22. BeverageCraft's prose, on the same subject, says 31 to 44. Beverage Factory says 2 to 4.

Two of those four are reconcilable. The rest are not.

Start with the easy one. Kegco's 5 to 7 and BeverageCraft's 15 to 22 are not in conflict at all, because they are counting different objects. BeverageCraft's table converts a 5 lb cylinder to 5 to 7 half barrels at 15.50 gallons, 10 to 14 quarter barrels at 7.75 gallons, and 15 to 22 five-gallon corny kegs. Kegco does not state which container it means, and no source reconciles the two figures; read side by side without checking the unit, they differ by roughly a factor of three.

Now the awkward one. BeverageCraft's chart puts a 5 lb cylinder at 15 to 22 five-gallon corny kegs; its own text elsewhere on the same page claims about 31 to 44. That is a straight doubling, and both cannot be right. The same page also says a North American lager takes half a pound of CO2 per half barrel, which is twice the efficiency implied by the half-pound-per-quarter-barrel rule it also states.

Which leaves Beverage Factory's 2 to 4 full-size kegs looking like an outlier. Beverage Factory adds that you land closer to 4 when the ambient temperature is colder, but does not say what its figure assumes; no source explains why the vendor and chart numbers diverge, or how much gas purging and carbonating consume.

The invisible gas budget: purging, carbonating, and slow leaks

Dispensing beer is not the only thing a homebrewer does with CO2. The same cylinder purges oxygen out of a keg before filling, force carbonates the beer once it's in there, and often pushes beer from fermenter to keg — MoreBeer lists all three uses alongside dispensing. None of the keg-per-tank charts account for any of it. The spread in real-world reports is wide. On the American Homebrewers Association forum, one brewer got roughly a year out of a 20 lb tank while running 38 four-gallon batches. Another user, who opened the cylinder valve only to force carbonate and to top up serving pressure, reported two years of pouring between fills of a 10 lb tank. Same hobby, very different gas budgets.

Slow leaks are hard to plan for, though no source in this comparison measures leak rate or standing losses. Beverage Factory's advice on this is specific and worth following: open the cylinder valve all the way, because the cylinder valve seals in two places. Temperature is the other quiet variable. Kegerators.com puts tank pressure at about 100 PSI at fill temperature, roughly 850 PSI at 70°F, and as high as 2000 PSI near 110°F, which is also why cylinders are filled to only 34% of their internal volume. Since tank pressure varies this much with temperature, a gauge reading in a warm space is not a direct measure of remaining gas; no source states how much usable gas is left once high-side pressure starts to fall.

Five measurements before you order anything

BeverageCraft publishes a 5 lb cylinder as 5.25 inches wide by 17.5 inches tall. Kegco publishes its own 5 lb aluminum tank as 5.5 by 18.25. Same nominal size, three quarters of an inch of difference in height and a quarter of an inch in diameter. As BeverageCraft and Kegco note in different ways, a tank that barely fits on paper may not fit in practice, and the listing will not tell you which.

So measure five things, not one:

• Tank diameter plus regulator body projection. The regulator hangs off the side of the valve and adds width beyond the cylinder, though no source in this comparison publishes that projection.
• Gas line bend radius. Gas line needs room past the regulator outlet before it has to change direction; no source in this comparison specifies a minimum bend radius.
• Vertical room to thread and rotate. You need clearance above the valve to seat the regulator nut and turn a wrench, which is more than the tank's height; no source specifies how much.
• Rear clearance for the compressor. Kegworks puts freestanding kegerator ventilation at 2 to 3 inches behind the unit — space the tank cannot borrow.
• Half an inch of margin, everywhere. Published dimensions are nominal and vary between makers, as the Kegco figures show.

Run those numbers and the fit answer usually arrives before the capacity one. A 20 lb cylinder at roughly 8 by 27.5 inches, per BeverageCraft's chart, is the size that decides whether the tank fits inside the cabinet or has to live outside it. Same logic that decides bar cart shelf clearance.

Tank by tank: what each size and bundle here is actually for

Start with the measure, not the capacity.

A 5 lb cylinder is the one that behaves like a kegerator part rather than an accessory. Published dimensions for the size run from BeverageCraft's 5.25 by 17.5 inches to Kegco's 5.5 by 18.25 inches, on the CGA-320 valve that is standard across sizes. No source in this comparison gives its empty weight or whether it ships filled.

The 10 lb version is the interesting middle. BeverageCraft puts a 10 lb cylinder at about 6.875 inches wide and 20 inches tall, and its chart runs a 10 lb tank up to 44 five-gallon corny kegs against 15 to 22 for a 5 lb. Larger tanks cost less per pound to fill — a point made on the American Homebrewers Association forum. At nearly 7 inches wide it may not fit a compact interior, though no source publishes the internal clearance of a named cabinet.

So why not just go 20 lb?

Because of the 8 by 27.5 inches. BeverageCraft's size chart gives the 20 lb those numbers, and that is the dimension deciding whether the tank fits inside the cabinet or has to live outside it. No source publishes its filled weight, though homebrewers describe hauling a big cylinder as a chore. Forum posters do describe a common arrangement of a 20 lb tank on the kegerator plus one or two 5 lb tanks for carbonating, travel and backup. No source in this comparison addresses leak rates or the price of a second cylinder.

At the small end, BeverageCraft puts a 16-gram CO2 cartridge at about a third of a corny keg and a 68-gram cartridge at 1 to 4 kegs, holding around 900 psi at room temperature.

Two more published numbers worth carrying to the order page:

• Kegco's 5 lb aluminum tank. Made from 6061-T6 high-strength aluminum, rated to 1800 PSI / 124 BAR service pressure and tested to 3000 PSI / 207 BAR.
• Cabinet capacity, the other half of the question. KegWorks puts residential kegerators at one half keg or 2 to 3 corny or sixtel kegs, and the $949.99 KOMOS Deluxe Kegerator at one half barrel keg or four corny kegs.

When 'just buy a 5 lb' is the wrong call

Three conditions break the 5 lb default, and each one has a different answer.

The first is a cabinet that won't take it. No source gives the internal clearance of a named compact unit, but the fix for a cabinet that won't take the tank is running the gas line out of the cabinet and standing a bigger cylinder outside, which one American Homebrewers Association forum thread recommends because a 5 lb on a multi-keg system means frequent refills at a worse price per pound. Measure the clear interior height first.

The second is force-carbonating. If you're carbonating regularly on top of dispensing, a 5 lb runs down faster, though no source quantifies how much gas force carbonating consumes; the 10 lb size, at about 6.875 by 20 inches per BeverageCraft, is the next step up. Kegerators.com stops at 10 lb for smaller kegerators; the same AHA thread told a six-keg keezer builder that 20 lb is plenty and still fits a keezer — a claim made without any measurement against a named cabinet.

Does a bigger bottle actually cost less?

That depends entirely on your supplier, and it's the third condition. Where a shop charges per fill rather than per pound — one brewer reported $19 to exchange either a 5 lb or a 10 lb, and said he would buy a 10 lb rather than pay $19 to fill a 5 lb — the bigger bottle can pay for itself, though reported prices conflict and no source gives the purchase price of anything but a 5 lb tank. Call before you order.

Who should buy what

• Commercial pre-carbonated kegs, one tap, tank inside: 5 lb, and a plain aluminum replacement if your current one is out of date on its D.O.T. test stamp.
• Homebrewers carbonating regularly: 10 lb, which Kegerators.com recommends as the largest for smaller kegerators.
• Multiple taps with floor space: 20 lb, plus a 5 lb for travel and as a backup — the arrangement forum posters describe.

This comparison is built on published specifications and listings, not on tanks anyone here has filled or weighed. So: buy the 5 lb, unless one of those three conditions is yours. Then check the DOT test date on the neck before you connect anything.