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Guide

How to keg homebrew and force carbonate

How to keg homebrew: clean and purge a corny keg, transfer without oxygen, force carbonate by the PSI chart, leak-check, serve and handle CO2 safely.

Updated November 2026 · 7 min read

Inside a keezer: a keg, CO2 cylinder and regulator in a chest freezer with a wooden collar
Photo: Matybsas, CC BY-SA 4.0, via Wikimedia Commons
The short version
  • Kegging replaces about 50 bottles with one 5 gal corny keg and carbonates in days instead of weeks.
  • Clean the keg, sanitize it, and push the sanitizer out with CO2 so the beer goes into an oxygen-free keg.
  • Set-and-forget carbonation: hold the beer cold at the PSI from the chart (about 11 psi at 38°F for 2.5 volumes) for 1–2 weeks.
  • Leak-check every connection with sanitizer spray; slow leaks empty CO2 tanks and flatten beer.
  • Keep CO2 cylinders upright and secured, always use a regulator, and ventilate if you smell or suspect a leak.

Learning how to keg homebrew is the upgrade most brewers wish they had made sooner. A 5 gal (19 L) ball-lock corny keg holds a whole batch, a CO2 cylinder and regulator carbonate it, and a fridge or kegerator keeps it cold and on tap. No priming sugar, no bottle conditioning wait and no washing 50 bottles.

This guide covers the full routine with a standard ball-lock keg. The cleaning and purging steps follow the American Homebrewers Association’s kegging introduction; carbonation pressures come from the empirical formula on our keg carbonation chart, checked against the BYO grid (40°F and 2.4 volumes: 11.2 psi). CO2 safety follows maker manuals.

What you need to start kegging

Kegging parts list

PartWhat to look forNotes
Corny keg, 5 gal ball lockNew or reconditioned; good O-rings and posts✓ Two kegs let you keep one on tap and one carbonating
CO2 cylinder5 lb is common; aluminum; in hydrostatic test date~ Ships empty; fill at a gas or welding supplier
RegulatorDual gauge (tank and output), 0–60 psi output range✓ Built-in pressure relief
Gas and liquid disconnectsBall lock (gas gray, liquid black)✓ Match your keg type
Gas and beer lineBeer line length matched to serving pressure~ Short lines pour foam
FaucetPicnic tap or forward-sealing faucet✓ Forward-sealing stays cleaner
Cold spaceKegerator, keezer or fridge✓ 34–40°F for serving
Cleaner, sanitizer, keg lubeLabel use✓ Lube O-rings lightly

Source: AHA: An introduction to kegging homebrew; Kegco and Taprite listings

A converted fridge holding two corny kegs, a CO2 tank and bottles of homebrew
Corny kegs, CO2 and a regulator fit in a converted fridge.Photo: Bruce Turner from AustinTX, CC BY 2.0, via Wikimedia Commons

A complete kegerator saves building time. Homebrew models such as the Kegco HBK309 series ship set up for ball-lock kegs; commercial Sanke kegs need a D-system coupler instead. A conversion kit turns a fridge or chest freezer into a keezer.

How do you keg homebrew, step by step?

  1. Confirm fermentation is finished

    Take two matching hydrometer readings a few days apart, just as for bottling. Kegs have pressure relief valves, but you still want a finished, stable beer. Cold crashing for 1–2 days first gives clearer beer.

  2. Clean the keg

    The AHA recommends disassembling the keg now and then, soaking the parts in warm water with cleaner for a few hours and replacing stained or smelly O-rings. Rinse well with hot water.

    Five Star PBW Alkaline Cleaner, 1 lbDbgogo Corny Keg O-Ring Rebuild Kit, 35 Pc with ToolLearn to Brew Keg Lube, 1 oz
  3. Sanitize and purge with CO2

    Fill the keg with no-rinse sanitizer at label dilution, close it, shake and flip it to wet the lid. Then connect gas at about 5 psi and push the sanitizer out through the liquid post until gas hisses through, as the AHA describes. The keg is now sanitized and full of CO2.

    Five Star Star San Acid Sanitizer, 32 oz
  4. Transfer the beer

    Siphon or pump the beer into the keg with minimal splashing, or do a closed transfer from a pressure-capable fermenter into the purged keg’s liquid post. Oxygen pickup at this step is the main cause of stale, dull hoppy beers.

  5. Seal and purge the headspace

    Close the lid, pressurize to about 20–30 psi to seat the lid O-ring, then pull the pressure relief valve a few times to vent air from the headspace.

  6. Leak-check

    Spray every connection, the lid and the posts with sanitizer and look for growing bubbles. Then close the tank valve for an hour and see whether the regulator’s output gauge drops.

  7. Carbonate

    Chill the keg to serving temperature and set the regulator to the chart pressure for your target volumes (below). Leave it on gas for 1–2 weeks.

  8. Balance and pour

    Lower to serving pressure if you carbonated higher, connect the beer line and pour. The first pint is often cloudy with yeast; after that it clears.

Keg carbonation chart: what PSI for kegging?

The pressure needed for a carbonation level depends on the beer’s temperature: cold beer absorbs CO2 at lower pressure. Read your beer’s temperature (not the room’s) and your style’s target volumes, and find the PSI in the chart.

Keg pressure (psi, sea level) by beer temperature and target CO2 volumes

Beer temp1.8 vol2.0 vol2.2 vol2.4 vol2.6 vol2.8 vol3.0 vol3.2 vol
32°F 0°C1.63.55.47.39.211.012.914.8
34°F 1.1°C2.34.36.38.210.212.114.116.0
36°F 2.2°C3.15.17.29.211.213.315.317.3
38°F 3.3°C3.96.08.110.212.314.416.518.6
40°F 4.4°C4.76.89.011.213.415.517.719.8
42°F 5.6°C5.57.710.012.214.416.718.921.1
44°F 6.7°C6.38.610.913.215.517.820.122.4
46°F 7.8°C7.19.511.814.216.619.021.323.7
48°F 8.9°C7.910.412.815.317.720.122.625.0
50°F 10°C8.711.313.816.318.821.323.826.3
52°F 11.1°C9.612.214.817.319.922.525.127.6
54°F 12.2°C10.413.115.718.421.123.726.329.0
56°F 13.3°C11.314.016.719.522.224.927.630.3

Formula: PSI = −16.6999 − 0.0101059·T + 0.00116512·T² + 0.173354·T·V + 4.24267·V − 0.0684226·V². Checked against the BYO grid (40°F and 2.4 vol: 11.19 psi by formula, 11.2 psi on the chart). Regulator gauges read relative to local air pressure. BYO notes that Denver needs about 3 psi over the sea-level chart; add roughly 0.5 psi per 1,000 ft. Sources: BYO: Carbonation priming chart; Brewer's Friend: Force carbonation chart; Brewers Association: Draught Beer Quality Manual.

PSI for 2.5 volumes by beer temperature

Sea-level gauge pressure from the empirical PSI formula (checked vs BYO)

34°F: 9.2 psi9.2 psi34°F38°F: 11.2 psi11.2 psi38°F42°F: 13.3 psi13.3 psi42°F46°F: 15.4 psi15.4 psi46°F50°F: 17.6 psi17.6 psi50°F55°F: 20.3 psi20.3 psi55°F
Source: BYO carbonation chart; GarageBrewer keg PSI formula

Regulator gauges read relative to local air pressure, so at altitude add about 0.5 psi per 1,000 ft; BYO notes Denver needs about 3 psi over the sea-level chart.

Keg carbonation chart and PSI calculatorEnter temperature, target volumes and altitude to get the regulator setting.

Force carbonation methods: slow, burst and shake

Three ways to carbonate a keg

MethodHowTimeRisk
Set and forgetHold at chart PSI and serving temperatureAbout 1–2 weeks✓ Lowest risk of overcarbonation
Burst carbonation30–40 psi for 24–36 hours, then vent to serving PSI2–4 days~ Easy to overshoot; check before serving
ShakeGas connected at higher pressure while rocking the kegMinutes to hours✗ Overcarbonation and foam are common
Carbonation stoneCO2 diffused through a stone in the keg1–2 days~ Needs the right lid or fitting

Source: AHA kegging introduction; BYO forced carbonation; Brewers Association Draught Beer Quality Manual

Set-and-forget is the method to start with. If you burst-carb, never exceed the keg’s or the fittings’ rated pressure, and remember that the regulator’s relief valve is a backup, not a setting.

Serving: temperature, pressure and foam

Foamy pours usually come from one of three things: beer warmer than the chart temperature, pressure set higher than the carbonation level needs, or beer lines too short to slow the flow. Most homebrew kegerators serve at 36–40°F (2–4°C) at roughly 10–12 psi, and 5–10 ft of 3/16 in. beer line gives enough resistance for a gentle pour. The Brewers Association’s Draught Beer Quality Manual explains line balancing in detail.

Close-up of chrome beer faucets on a stainless panel
Faucets pour best when temperature and line length match the pressure.Photo: kvanhorn, CC BY 2.0, via Flickr

Forward-sealing faucets keep beer out of the faucet body between pours and stay cleaner. Clean beer lines regularly with a line cleaner; dirty lines grow bacteria that cause off-flavors.

CO2 safety

CO2 is stored at high pressure, and the gas itself displaces oxygen in closed spaces. Basements, closets and keezers in small rooms deserve extra care.

Two stainless kegs beside a green gas cylinder seen from above
Keep gas cylinders upright and secured.Photo: Simon Leung gg, CC BY-SA 4.0, via Wikimedia Commons
CO2 cylinders and pressureKeep cylinders upright and secured, and always use a CO2-rated regulator (US CO2 tanks use the CGA 320 valve fitting); never connect a cylinder straight to a keg. Store tanks cool and away from heat. CO2 displaces oxygen and collects low: ventilate, close the tank valve and leave the room if a tank leaks. Never exceed a fermenter’s or keg’s rated pressure.Source: Kegco: Everything you need to know about CO2; OSHA hazard bulletin on CO2
  • Keep the cylinder upright and chained or strapped so it can’t fall.
  • Always use a regulator; never connect a cylinder directly to a keg.
  • Store cylinders away from heat and direct sun; don’t leave them in a hot car.
  • If you suspect a big leak, close the tank valve, ventilate and leave the area.
  • Consider a CO2 monitor where the keezer or tank lives in a small room.

Mistakes to avoid

  • Skipping the leak check. A slow leak can empty a 5 lb tank in days.
  • Carbonating at room temperature at serving pressure. Warm beer needs much more pressure for the same carbonation; follow the chart for the beer’s real temperature.
  • Shaking aggressively. It overshoots and foams for days.
  • Short beer lines. Too little resistance means foam at any pressure.
  • Mixing up gas and liquid posts. Disconnects are marked; forcing the wrong one damages the post.
  • Ignoring O-rings. Dry or cracked O-rings leak; lube lightly and replace when worn.
  • Letting lines go uncleaned. Clean them between kegs.

Who should keg, and with what

  • Brewing every month or two: two corny kegs, a 5 lb cylinder, a dual-gauge regulator and a kegerator.
  • Already own a spare fridge or chest freezer: a conversion kit or collar build (keezer).
  • Small space: mini kegs or a single-tap kegerator.
  • Still want bottles for sharing: keg first, then fill bottles from the keg with a counter-pressure filler.

Bottling is still the right choice for aging strong beers or sending beer to competitions; compare the two in how to bottle homebrew. The background on volumes and pressure is in carbonation explained, and every kegerator and keg part is in the switching to kegs section.

Gear picks for this guide: best homebrew keg systems and best CO2 regulators for kegging.

VerdictClean, sanitize and purge the keg with CO2, transfer without splashing, leak-check, then hold the beer cold at the chart pressure for a week or two. Keep the cylinder upright and secured and the lines clean, and kegging is easier than bottling.
ABV calculatorWork out ABV from OG and FG with the standard and high-gravity formulas, hydrometer temperature correction,…Keg carbonation chart and PSI calculatorKeg carbonation chart and calculator: regulator PSI by beer temperature and CO2 volumes, with an altitude…

Questions

What PSI should I keg my homebrew at?
It depends on beer temperature and the carbonation level you want. For 2.5 volumes at 38°F, the chart gives about 11 psi at sea level; add about 0.5 psi per 1,000 ft of altitude.
How long does it take to force carbonate a keg?
About 1–2 weeks at serving pressure and temperature. Burst carbonation at higher pressure can do it in 2–4 days but is easier to overshoot.
How long does a 5 lb CO2 tank last?
It depends mainly on leaks and on how much you carbonate versus serve. With leak-free connections, a 5 lb cylinder typically handles several 5 gal kegs. A leak can empty it in days, so leak-check every connection.
Do I need priming sugar if I keg?
No. Kegged beer is carbonated with CO2 from the cylinder. Some brewers naturally carbonate kegs with priming sugar, using about half the bottling amount, but it takes as long as bottle conditioning.
Why is my kegged beer foamy?
Usually the beer is warmer than the chart temperature, the pressure is too high for its carbonation, or the beer line is too short. Check the temperature first, then line length.
Can a homebrew kegerator take commercial kegs?
Homebrew kegerators set up for ball-lock corny kegs need a D-system coupler and a fitting change to tap most US commercial kegs. Check the model’s manual.

Sources

  1. AHA: An introduction to kegging homebrew
  2. BYO: Carbonation priming chart (force carbonation grid)
  3. BYO: Forced carbonation
  4. Brewers Association: Draught Beer Quality Manual
  5. Brewer’s Friend: Keg carbonation calculator
  6. Kegco: Everything you need to know about CO2
  7. EPA: Star San label, Reg. No. 65001-1