CO2 Tank Duration Calculator

Enter your tank size, keg volume, CO2 usage per keg, and weekly dispense rate to see exactly how long your CO2 supply will last.

Created by Luis GonzalezLast updated: June 17, 2026

How to Use This Calculator

1
Enter Your Tank and Keg Details
Input your CO2 tank size in pounds (common sizes: 5, 10, or 20 lb), keg volume in gallons (5 gal for Cornelius, 15.5 gal for half-barrel), and the CO2 used per keg in ounces (typically 6-10 oz for a 5-gallon keg).
2
Set Usage Rate and Review Results
Enter how many kegs you dispense per week and your tank refill cost. The calculator instantly shows kegs per tank, weeks until refill, total beer output, CO2 cost per keg, and annual CO2 expenses.

Example Calculation

A homebrewer in 2026 wants to plan refill trips for a 5 lb CO2 tank dispensing 5-gallon Cornelius kegs at 8 oz of CO2 per keg, going through 2 kegs per week with a $20 refill cost.

Tank Size (lb)

Keg Size (gal)

CO2 Used per Keg (oz)

Kegs Dispensed per Week

Tank Refill Cost ($)

Results

Kegs per Tank

10.0

Weeks Until Refill

5.0 wks

Total Beer

50.0 gal (400 pints)

CO2 Cost per Keg

$2.00

Annual CO2 Cost

$208

Tips

Check for Leaks After Every Keg Change

CO2 leaks are the leading cause of unexpectedly short tank life. After connecting a new keg, spray all fittings with soapy water and watch for bubbles. A slow leak can drain a 5 lb tank (80 oz) in days rather than the expected 5 weeks.

Match Serving Pressure to Beer Style

Serving at the correct pressure (10-12 PSI for ales, 12-15 PSI for lagers at 38-40 degrees F) prevents over-carbonation and gas waste. Every 2 PSI above optimal increases CO2 usage by roughly 10-15%, shortening your tank life from 10 kegs down to 8 or fewer.

Upgrade Your Tank Size to Save Money

A 20 lb tank costs about $30-35 to refill in 2026 but dispenses 40 kegs at 8 oz per keg, compared to 10 kegs from a 5 lb tank at $20. That cuts your CO2 cost per keg from $2.00 to roughly $0.88 — a 56% savings.

Store Tanks Upright in Cool Areas

High temperatures increase internal tank pressure, potentially triggering the safety relief valve and venting gas. Keep tanks upright, secured, and below 120 degrees F. A garage or basement that stays under 80 degrees F is ideal for maximizing your CO2 supply.

Understanding CO2 Tank Duration for Draft Systems in 2026

The CO2 Tank Duration Calculator helps homebrewers and kegerator owners estimate exactly how many kegs a tank can dispense, when to schedule refills, and how much CO2 costs per keg. Whether you run a single Cornelius keg at home or manage multiple taps at a bar, knowing your tank's lifespan prevents mid-pour gas outages and helps budget for annual CO2 expenses. With CO2 refill prices varying in 2026, tracking cost per keg is especially valuable.

How the CO2 Tank Duration Formula Works

The calculator uses a straightforward set of formulas to convert tank weight into actionable dispensing metrics:

Total CO2 Available (oz) = Tank Size (lb) x 16
Kegs per Tank = Total CO2 Available / CO2 Used per Keg
Total Beer (gal) = Kegs per Tank x Keg Size (gal)
Weeks Until Refill = Kegs per Tank / Kegs per Week
CO2 Cost per Keg = Refill Cost / Kegs per Tank
Annual CO2 Cost = (52 / Weeks Until Refill) x Refill Cost

Tank Size	CO2 (oz)	Kegs (at 8 oz/keg)	Weeks (at 2/wk)	Cost/Keg ($20 refill)
5 lb	80	10.0	5.0	$2.00
10 lb	160	20.0	10.0	$1.25*
20 lb	320	40.0	20.0	$0.88*

*Estimated based on typical 2026 refill pricing of $25 for 10 lb and $35 for 20 lb tanks.

💡 Force carbonating a keg adds 4-8 oz of CO2 beyond dispensing. If you force carb, increase your "CO2 Used per Keg" input to 12-16 oz for a more accurate duration estimate.

CO2 Tank Sizing and Cost Optimization

Choosing the right tank size in 2026 is a balance between upfront cost, portability, and refill frequency. A 5 lb tank is the most portable and fits easily inside most kegerator cabinets, but at 10 kegs per fill, weekly dispensers will visit the supply shop monthly. A 20 lb tank dispenses 40 kegs and costs roughly $35 to refill, cutting your per-keg CO2 cost to $0.88 compared to $2.00 for a 5 lb tank — a 56% reduction.

For homebrewers dispensing 2 kegs per week, the annual CO2 cost ranges from about $208 with a 5 lb tank to approximately $91 with a 20 lb tank. That $117 annual savings covers the cost of a larger tank within the first year.

💡 Keep a backup 2.5 lb or 5 lb "emergency" tank on hand. Running out of CO2 mid-keg exposes beer to oxygen, which causes staling within 24-48 hours. The small investment in a backup tank protects your entire batch.

Safety and Maintenance Best Practices

CO2 tanks require periodic hydrostatic testing every 5 years per DOT regulations. Always store tanks upright and secured to prevent tipping, which can damage the valve assembly. In confined spaces like closets or chest freezers, ensure adequate ventilation — CO2 is heavier than air and displaces oxygen, creating an asphyxiation risk if a tank leaks in an enclosed area. Replace O-rings and washers annually, and always use food-grade CO2 for beverage dispensing.

Frequently Asked Questions

How many kegs can a 5 lb CO2 tank dispense?

A 5 lb CO2 tank holds 80 ounces of gas. At 8 oz per 5-gallon keg (a typical usage rate), it dispenses exactly 10 kegs. If your system uses more CO2 per keg due to higher serving pressure or leaks, you may get 7-9 kegs instead. Larger half-barrel kegs (15.5 gal) require roughly 16-20 oz of CO2 each, reducing output to 4-5 kegs per tank.

How long does a 5 lb CO2 tank last for homebrewing?

Duration depends entirely on your dispensing rate. At 2 kegs per week with 8 oz CO2 per keg, a 5 lb tank lasts 5 weeks. At 1 keg per week, it lasts 10 weeks. Light users dispensing one keg every two weeks can stretch a single 5 lb tank to nearly 5 months. Leaks are the most common reason a tank empties faster than expected.

What is the typical CO2 usage per keg?

For a standard 5-gallon Cornelius keg served at 10-12 PSI, typical CO2 usage is 6-10 ounces. The exact amount depends on serving pressure, temperature, line length, and whether you are also force-carbonating the beer (which uses an additional 4-8 oz). A half-barrel (15.5 gal) keg uses roughly 16-20 oz of CO2 per keg.

How much does it cost to refill a CO2 tank in 2026?

In 2026, a 5 lb CO2 tank refill typically costs $15-$25 at homebrew supply stores or welding shops. A 10 lb tank costs $20-$30, and a 20 lb tank runs $30-$45. Larger tanks offer better cost efficiency per ounce of CO2. Some stores offer exchange programs where you swap your empty for a pre-filled tank at a discount.

What factors shorten CO2 tank life the most?

The three biggest factors are system leaks, excessive serving pressure, and force carbonation. A small leak at a connection can empty a tank in 1-3 days. Serving above 14 PSI wastes gas through over-carbonation. Force carbonating each keg adds 4-8 oz of extra CO2 usage. Regular leak checks and proper pressure settings are the best ways to maximize tank life.

Should I get a 5 lb, 10 lb, or 20 lb CO2 tank?

For 1-2 kegs per week, a 5 lb tank works but requires monthly refills. A 10 lb tank doubles your capacity and is the sweet spot for most homebrewers, lasting about 10 weeks at 2 kegs per week. A 20 lb tank is best for high-volume users or those who dislike frequent refill trips, lasting roughly 20 weeks at the same rate. Larger tanks also have a lower cost per keg of CO2.