Refrigerant Line Sizing Calculator
Enter your system's BTU load and equivalent line length, and get a recommended suction and liquid line diameter built for new installs and line-set replacements.
- Covers All 8 Stocked Refrigerants
- Built for Field Use
- No Login Required
- Updated for Current A2L Data
How the Pipe Sizing Calculator Works
Three steps between you and a verified saturation reading no chart flipping required.
Enter your system's BTU load
Use the equipment's rated capacity, or run the BTU calculator first if you're still sizing the system itself.
Enter equivalent line length and elevation
Include fitting equivalents, not just straight-line distance, plus any vertical rise between indoor and outdoor units.
Get recommended line diameters
The calculator returns separate suction and liquid line sizing based on your inputs.
Why Line Sizing Affects More Than Just Fit
An undersized line set doesn't just look wrong on the wall it restricts refrigerant flow enough to cost real system capacity.
Suction Line vs. Liquid Line Sizing
These two lines are sized independently and for different reasons. Suction line diameter is driven primarily by oil return velocity and pressure drop, while liquid line diameter is driven mostly by pressure drop and subcooling loss over distance which is why they're rarely the same size on a given system.
Equivalent Length vs. Straight-Line Distance
Every elbow, tee, and vertical rise in a line run adds resistance equivalent to some additional straight-line footage, and ignoring that when sizing leads to an undersized recommendation on a run with a lot of fittings. Always calculate equivalent length, not just the physical measured distance, before running this calculator.
Vertical Rise and Oil Return
Significant elevation change between the indoor and outdoor unit affects both pressure drop and the refrigerant velocity needed to carry compressor oil back to the compressor. Long vertical suction risers in particular may need a smaller diameter than a horizontal run of the same length to maintain adequate oil return velocity.
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Frequently Asked Questions
Yes convert elbows, tees, and other fittings to their equivalent straight-line footage and add that to your measured distance before running the calculator.
Usually, yes. They're sized independently based on different factors, so it's common for a system to need different diameters for each.
Yes significant vertical rise, especially on the suction side, can require a different diameter to maintain proper oil return velocity.
Yes, refrigerant type is a required input since it affects the sizing calculation.
Need the Refrigerant to Match?
Every calculator links straight to the in-stock cylinder for that refrigerant.