How long should my beer line be?
The idea is simple: the regulator pushes at, say, 12 psi, and by the time the beer reaches the faucet you want almost all of that used up — about 1 psi left to push it into the glass — so it arrives slowly enough to stay in solution. Lifting the beer costs some of the pressure (0.44 psi per foot of rise — hydrostatic head, which every chart rounds to 0.5) and the line's friction costs the rest. Every source prints the same equation:
length = (keg psi − rise × 0.44 − 1) ÷ resistance per foot
For the common case — 12 psi, a floor keg with the faucet 2 ft above its middle, 3/16" vinyl — the lift costs 0.9 psi, leaving 10.1 for the line to absorb. And that's where the sources stop agreeing, because the equation has one number in it that nobody measures the same way.
Why every calculator gives a different length
"Resistance per foot" for 3/16" vinyl is 3 psi/ft on BeerSmith, 2.7 on Kegerators.com and Brewer's Friend, and 2.2 on KegWorks — a 36% spread, which none of them mentions. Same keg, same faucet, and the "correct" line is anywhere from 3.4 to 4.6 ft depending on whose page you opened:
| Tubing | Source | psi per foot | Line for 12 psi, 2 ft tower |
|---|---|---|---|
| 3/16" ID vinyl (4.8 mm) | BeerSmith | 3 | 3.4 ft · 1 m |
| Kegerators.com / Brewer’s Friend | 2.7 | 3.7 ft · 1.1 m | |
| KegWorks | 2.2 | 4.6 ft · 1.4 m | |
| 1/4" ID vinyl (6.4 mm) | BeerSmith | 0.85 | 11.9 ft · 3.6 m |
| Kegerators.com / Brewer’s Friend | 0.7 | 14.5 ft · 4.4 m | |
| KegWorks | 0.65 | 15.6 ft · 4.7 m | |
| 5/16" ID vinyl (7.9 mm) | KegWorks | 0.4 | 25.3 ft · 7.7 m |
| Kegerators.com / Brewer’s Friend | 0.17 | 59.6 ft · 18.2 m | |
| 3/8" ID vinyl (9.5 mm) | KegWorks | 0.2 | 50.6 ft · 15.4 m |
| Kegerators.com / Brewer’s Friend | 0.11 | 92 ft · 28.1 m | |
| 3/16" ID barrier / polyethylene | BeerSmith | 2.2 | 4.6 ft · 1.4 m |
| 1/4" ID barrier / polyethylene | BeerSmith | 0.5 | 20.2 ft · 6.2 m |
| KegeratorOnline | 0.3 | 33.7 ft · 10.3 m | |
| 1/4" OD stainless | BeerSmith | 2 | 5.1 ft · 1.5 m |
| KegWorks | 1.2 | 8.4 ft · 2.6 m | |
| 5/16" OD stainless | BeerSmith | 0.5 | 20.2 ft · 6.2 m |
| KegWorks | 0.3 | 33.7 ft · 10.3 m | |
| 3/8" OD stainless | BeerSmith | 0.2 | 50.6 ft · 15.4 m |
| KegWorks | 0.12 | 84.4 ft · 25.7 m |
Constants exactly as each source prints them (checked 25 Aug 2026); lengths computed by this page's engine with hydrostatic lift and 1 psi at the faucet.
Kegerators.com goes one better: its table says 2.7 psi/ft, and its worked example — 10 psi, 1.5 ft tower, ten seconds a pint — says "around 8 feet." Its own constant makes that 3.1 ft. The example is right and the constant is wrong, and the reason is the next section.
Resistance isn't a property of the tube
Pressure loss in a pipe depends on how fast the liquid is moving. In the turbulent flow a beer line is in, it rises with roughly the 1.75th power of the flow rate — pour twice as fast and the same foot of line resists three and a half times as hard. So "3 psi per foot" is true at exactly one pour speed, and each source measured, copied or guessed theirs at a different one. Run the actual fluid mechanics (Darcy–Weisbach, smooth pipe, beer at 38 °F) and the constant becomes a curve:
| Pour speed | 3/16" ID vinyl (4.8 mm) | 1/4" ID vinyl (6.4 mm) | 5 mm ID |
|---|---|---|---|
| 6 s per pint | 2.98 psi/ft → 3.4 ft 1 m | 0.76 psi/ft → 13.3 ft 4.1 m | 2.36 psi/ft → 4.3 ft 1.3 m |
| 8 s per pint | 1.8 psi/ft → 5.6 ft 1.7 m | 0.46 psi/ft → 22.1 ft 6.7 m | 1.43 psi/ft → 7.1 ft 2.2 m |
| 10 s per pint | 1.22 psi/ft → 8.3 ft 2.5 m | 0.31 psi/ft → 32.6 ft 9.9 m | 0.97 psi/ft → 10.5 ft 3.2 m |
| 12 s per pint | 0.89 psi/ft → 11.4 ft 3.5 m | 0.23 psi/ft → 44.8 ft 13.7 m | 0.7 psi/ft → 14.4 ft 4.4 m |
12 psi, 2 ft tower, beer at 38 °F assumed 1.5× the viscosity of water. Blasius friction for smooth tubing. Computed by this page's engine.
At the Brewers Association's 2 oz per second — an 8-second pint — 3/16" vinyl is about 1.8 psi/ft, the low end of every published constant, and the line comes out at 5.6 ft. Slow the pour to 10 seconds and it's 1.2 psi/ft and 8.3 ft — which is the "just use 8–10 feet" advice the forums have converged on by trial and error, and the reason Mike Soltys' fluid-dynamics calculator is the one people trust. This calculator does the same physics, shows the published range beside it, and headlines the longest of the two. Tool and article agree on that because there's no contest: a line that's a foot long pours slowly; a line that's a foot short pours foam.
Beer at 12 psi holds 2.6 volumes of CO₂ at 38 °F. The moment it's somewhere at lower pressure, gas wants out. A balanced line drops the pressure gradually along its length so that the beer is moving slowly by the time it's at atmospheric pressure in the glass; a short line drops it all at once at the faucet, where the beer is moving fast, and the CO₂ breaks out as foam. Nothing about the beer changed — only where the pressure was lost.
3/16" or 1/4" beer line?
Narrower tubing resists far more per foot (about (4/3)4.75 ≈ 4× between these two), so 1/4" needs three or four times the length for the same pressure. For a kegerator with the keg under the faucet, 3/16" is the right answer at anything under about 16 psi; 1/4" and up are for long runs to a remote faucet, where you want the low resistance. Lengths for an 8-second pint, 2 ft tower:
| Regulator | 3/16" ID (4.8 mm) | 1/4" ID (6.4 mm) | 5/16" ID (7.9 mm) |
|---|---|---|---|
| 8 psi | 3.4 ft · 1 m | 13.3 ft · 4.1 m | 38.5 ft · 11.7 m |
| 10 psi | 4.5 ft · 1.4 m | 17.7 ft · 5.4 m | 51.1 ft · 15.6 m |
| 12 psi | 5.6 ft · 1.7 m | 22.1 ft · 6.7 m | 63.6 ft · 19.4 m |
| 14 psi | 6.7 ft · 2.1 m | 26.4 ft · 8 m | 76.2 ft · 23.2 m |
| 16 psi | 7.8 ft · 2.4 m | 30.8 ft · 9.4 m | 88.8 ft · 27.1 m |
| 20 psi | 10.1 ft · 3.1 m | 39.5 ft · 12 m | 113.9 ft · 34.7 m |
Physics at 8 s per pint, 38 °F, sea level. A 20 psi wheat beer wants 10 ft of 3/16" — which is why high-carbonation styles are the ones that foam. Computed by this page's engine.
What if I just cut it long?
Then it pours a little slower, and that's all. This is why the honest answer to every line-length question is cut long, pour, and trim: a line that's too long is a mild inconvenience you can fix with scissors in thirty seconds, and a line that's too short is a glass of foam you can't fix without buying tubing.
| 3/16" line on 12 psi | Pours a pint in |
|---|---|
| 3 ft · 0.9 m | 5.6 s |
| 5 ft · 1.5 m | 7.5 s — the length most kits ship with |
| 8 ft · 2.4 m | 9.8 s |
| 10 ft · 3 m | 11.1 s |
| 12 ft · 3.7 m | 12.3 s |
2 ft tower, 38 °F. Faster than about 6 s a pint foams regardless of line length. Computed by this page's engine.
On 12 psi, the 5 ft of 3/16" line most kegerator kits ship with pours a pint in about 7.5 seconds — fast enough to foam. Ten feet pours it in 11. In between, each extra foot costs about 0.7 s per pint, so the penalty for cutting two feet too long is one second of your life per beer, and the penalty for cutting two feet too short is the beer. Start at the longest number this page gives you and take six inches off at a time.
My kegerator foams — is it the line?
Maybe, but check the cheaper causes first, in this order. Temperature: a tower that isn't cooled holds a few ounces of warm beer in the line, and the first pour of the day foams no matter what the line length is; a fan or a tower cooler fixes it, tubing doesn't. Pressure versus carbonation: if the beer was burst-carbed and never settled, or the fridge runs colder than you thought, it holds more gas than the regulator is now set to hold, and it will foam until it out-gasses. Then the line, and only then cleanliness — a dirty faucet or a failed dip-tube o-ring (CO₂ injected straight from the headspace into the beer line) both foam, and both look like a pressure problem.
The one thing not to do is the thing every kit owner does first: turn the regulator down. It fixes the pour for a day. Then the beer, which was carbonated to 2.6 volumes at 12 psi, spends the week out-gassing toward the 2.2 volumes that 8 psi holds at 38 °F — and now you have a flat beer that still foams. The regulator sets the carbonation; the line sets the pour. The keg calculator will tell you the pressure your beer needs (11.2 psi for 2.5 volumes at 38 °F); this page tells you the line that pours it. Change the one that's wrong.
The honest summary: this page's physics is textbook and its inputs aren't. Tubing sold as 3/16" varies by a few thousandths, the beer's viscosity is an assumption, the faucet's own restriction is folded into "1 psi," and your idea of a good pour isn't anyone else's. That's why the answer is a starting length, not a cut list — and why it errs long.