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CO2 Beer Line Length Calculator

Enter your CO2 pressure, line resistance and rise height to get the balanced line length.

Result

4.3 ft
9.50 psi
12.00 psi

How it is calculated

A balanced line uses up the keg pressure along its length. The tool first subtracts a fixed 1 psi allowance and 0.5 psi for every foot of rise: needed = psi − 1 − 0.5 × rise. It then divides by the line's resistance: length = needed ÷ resistance. Pressure is in psi, rise (keg level to tap) in feet, resistance in psi per foot, and the length comes out in feet with one decimal. If you leave resistance empty it uses 2.2 psi/ft, and an empty rise counts as 1 ft. Resistance depends on the tubing's inner diameter, so take the figure from your line's supplier. If the pressure is too low for the rise, nothing is left to burn off and no result is given.

Worked example

A kegerator runs at 12 psi, the tap sits 3 ft above the keg, and the line is rated 2.2 psi/ft. Needed resistance: 12 − 1 − 0.5 × 3 = 9.50 psi. Line length: 9.50 ÷ 2.2 = 4.318, shown as 4.3 ft. In practice you would cut the line a little over that and trim it after tasting a pour; too short a line pours foam, too long a line pours slowly.

Try this example →

Common mistakes

  • Using the wrong resistance: the tool assumes 2.2 psi/ft when the field is empty, but thinner or thicker tubing has a different rating.
  • Entering the rise in metres or inches; it must be in feet.
  • Entering the pressure in bar or kPa instead of psi, which gives a wildly short line.
  • Measuring the rise from the floor rather than from the keg level to the faucet.
  • Cutting to the exact result and not leaving spare length; trim in small steps, since foam means the line is too short.

About this calculator

A “balanced” draft system is one where beer pours smoothly with a proper head instead of gushing foam, which requires the beer line's resistance to fluid flow to match the CO2 pressure driving it, accounting for the height difference between the keg and the tap. Vinyl beer line has a known resistance per foot that depends on its diameter (you enter it in psi/ft; the calculator starts with 2.2 psi/ft), so the required line length can be worked out from the applied pressure minus 1 psi for the faucet and fittings and minus 0.5 psi for each foot of rise in elevation, divided by that resistance.

Get the line length wrong and the pour is either an oversized foam mess (too short/too little resistance) or comes out flat and slow (too long/too much resistance). Bar owners, brewers, and kegerator hobbyists use this calculation whenever they're building or reconfiguring a draft system to size the beer line correctly for their specific CO2 pressure and keg placement.

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Comments (1)

  • Editorial team

    Set the pressure from the beer first, then size the line, rather than raising pressure to fix a foamy pour. Serving pressure follows the beer temperature and carbonation level, and this tool only works out how much line is needed to absorb it. Each 2 psi of pressure changes the answer by about 0.9 ft at 2.2 psi/ft: 12 psi gives 4.3 ft, while 10 psi gives 3.9 ft. What serving pressure and tubing are you running?

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