Calculator
CO2 tank lifespan: how long will yours last?
Plug in your tank size, serving pressure, and how often you tap a fresh keg. Out comes months-until-refill, refills per year, and annual CO2 cost. Plus a side-by-side of 5lb vs 10lb vs 20lb tanks for your specific usage.
Tank size comparison for your usage
Side-by-side of the three common tank sizes at your current settings:
| Tank size | Kegs per tank | Months to refill | Refills/year | Annual cost |
|---|---|---|---|---|
| 5 lb | — | — | — | $0 |
| 10 lb | — | — | — | $0 |
| 20 lb | — | — | — | $0 |
How the calculation works
At typical serving pressure (10-12 PSI), a CO2 tank delivers about 0.65 pounds of gas per half-barrel keg you dispense. That's the "pure dispensing" cost, the gas that actually leaves through the tap as beer pours.
On top of that, a home system has overhead: pressure maintenance on the keg between pours, micro-leaks at fittings, occasional faucet drips while changing out kegs. Our default "average" multiplier of 1.4x reflects the typical home setup with one slow leak that you haven't found yet. A genuinely tight system uses 1.0x; a loose one with a visible overnight pressure drop runs 2.0x or higher.
Higher PSI scales gas consumption roughly linearly. Serving at 14 PSI uses about 17% more gas than 12 PSI. Nitro-style serving (30+ PSI) uses dramatically more, but most nitro setups run on a separate beer-gas blend, not pure CO2, so we exclude that case.
Annual cost assumes the typical welding-supply refill rates: $22 for a 5lb refill, $28 for a 10lb, $40 for a 20lb. Homebrew-shop refills typically run 30-50% more, but the cost-per-pound is the cheapest at the largest tank size, which is why heavy users converge on 20lb tanks.
What this calculation doesn't capture
- One-time tank purchase or deposit ($40-80 for a 5lb, $80-130 for 10lb, $150-220 for 20lb). Most are one-and-done; only refill cost is recurring.
- Travel time to and from the refill shop. If you live 30 minutes from a welding supply, the time cost of refills favours larger tanks.
- Storage space. A 20lb tank is 3 feet tall; not every garage or kitchen has room.
- Nitrogen stout serving (separate beer-gas blend, different tank, different math).
- Force-carbonating fresh kegs from scratch (homebrew use case; uses meaningfully more gas).
When the numbers say one thing but you should still upgrade
Even when 5lb math says "refills every 6 months, fine for me", most homeowners who own a 5lb tank end up upgrading to 10lb within 18 months. The reason is rarely the refill cost; it's the inconvenience of running out mid-party. A 10lb tank means roughly one refill per year for a typical household, which is hard to mess up timing-wise. A 5lb tank can empty during a Saturday afternoon and turn a party into an emergency.
20lb tanks make sense for: heavy hosts (3+ parties per month), outbuilding setups (don't want to schlep a tank back to the house every few months), and anyone who wants to refill once every 18-24 months. The downside is bulk; a 20lb is 3 feet tall and roughly the diameter of a dinner plate.
Related reading
For the cornerstone CO2 article: 5 lb vs 10 lb vs 20 lb CO2 tank for a kegerator. For line-balancing context (which affects gas use): beer line length calculator. For the broader cost picture: kegerator ROI calculator.
For real-world data: our 2026 Home Bar Cost Report tracks annual CO2 cost across the home kegerator population ($40-60/year median, in line with the typical 10lb tank refilling 2-3 times annually). Useful sanity check against your calculator output.
Topic hubs that compound this calculator: CO2 systems (the home for every CO2-related note) and first-time setup (where pressure-testing prevents the leaks that wreck CO2 lifespan in the first place).
People also ask
How long does a 5lb CO2 tank last on a home kegerator?
For a typical home setup at 12 PSI with average system tightness, a 5lb tank lasts about 5-7 half-barrel kegs, or roughly 5-7 months at 1 keg per month. Heavy hosts (3+ kegs/month) burn through a 5lb in 6-8 weeks. The calculator above gives you the exact number for your specific usage.
How long does a 10lb CO2 tank last?
10-14 half-barrel kegs at typical home pressure, which works out to 10-14 months at 1 keg/month, or roughly 4 months at 3 kegs/month. This is why 10lb is the default for most home kegerators: one refill per year matches a once-yearly maintenance routine that's easy to remember.
How long does a 20lb CO2 tank last?
22-28 kegs at typical home pressure. A casual user buying 1 keg per month would refill a 20lb tank every 22-28 months, basically every 2 years. Heavy hosts at 3 kegs/month still get 7-9 months between refills. 20lb tanks make sense if you have the space and hate refill trips.
How much does it cost to refill a CO2 tank?
Welding supply shops are cheapest: $20-25 for a 5lb refill, $25-30 for 10lb, $35-45 for 20lb. Homebrew shops charge 30-50% more for the same service. Avoid anywhere that doesn't specify food-grade CO2; industrial CO2 contains dye additives that taste bad and aren't safe for beer.
Why is my CO2 tank emptying faster than it should?
Almost always a slow leak. Soap-test every joint while the system is pressurised: regulator-to-tank junction, gas-line clamps, coupler quick-disconnect, keg ring. A pressurised system that loses noticeable pressure overnight has a leak, even if you can't hear it. The second most common cause is leaving the regulator at higher pressure than you need, which sends gas through the system faster.
Can I leave my CO2 tank turned on between uses?
Yes, and you should. The tank valve is designed to stay open; only the kegerator regulator manages serving pressure. Cycling the tank valve on and off shortens the o-ring lifespan and increases the chance of slow leaks at the junction. Leave the tank fully open, let the regulator do its job.
Sources & references
Claims in this article cross-check against the following. We link out so you can verify.
- Draught Beer Quality Manual (4th Edition) — Brewers Association manufacturer
- Kegerator CO2 Consumption Patterns — KegWorks manufacturer
- Home Bar Cost Report 2026: Annual CO2 spend benchmarks — Kegnotes research