Line set charge calculator

How the charge addition is calculated

The outdoor unit ships with enough refrigerant for the coil, the condenser and a set length of line. Every foot past that length needs more, at a rate the manufacturer prints in the installation instructions. The calculator does that arithmetic and, next to it, shows how much liquid the extra liquid line physically holds.

Charge to add

(total length - factory length) x oz per ftThis is the manufacturer's method. Goodman TP-107M writes it for its residential R-410A units as (L - 15) ft x 0.6 oz per ft, which gives 21.0 oz for a 50 ft line.

Pounds

oz / 16Scales read in pounds and ounces, so the result is shown both ways.

Liquid in one foot of line (reference)

pi / 4 x ID² / 144 x liquid density x 16ID is the inside diameter of annealed ACR tube from the Copper Development Association handbook, 0.311 in. for 3/8 in. OD. Density is saturated liquid at the temperature you enter, from CoolProp. For R-410A in 3/8 in. line at 100°F that is 0.52 oz per foot.

Rate against physics

manufacturer rate vs liquid in the lineGoodman lists its 0.6 oz per foot for the 3/8 in. liquid line alone, above the 0.52 the physics gives at 100°F, and the guide does not state the basis. Its table then steps the rate up to 0.78 oz per foot once a suction line as large as 1-1/8 in. is counted. Either way, the rate is what goes on the scale.

Line lengths and what the line holds

Goodman's published R-410A numbers, 15 ft and 0.6 oz per foot of 3/8 in. liquid line, at five run lengths, next to the liquid the extra line holds at 100°F.

On the 50 ft run the rate asks for 21.0 oz while the extra liquid line holds about 18.2 oz. Goodman labels its rate for the liquid line alone and does not give the basis for the 2.8 oz gap. The rate is the number that goes on the scale.

Liquid one foot of annealed ACR tube holds at 100°F liquid, in ounces. Physics only, for checking that a rate is in the right range.

R-32 liquid is lighter than R-410A, so 3/8 in. line holds about 9 percent less of it. That is one reason an R-410A rate cannot be carried to an A2L unit. The other is that the A2L system's total charge has a ceiling, which the installation manual states.

Standards and data sources

• Goodman TP-107M, Long Line Set Application R-410A (September 2020) - the worked example. All residential R-410A outdoor units in that guide are factory charged for 15 ft of line set, and the addition is (L - 15) ft x 0.6 oz per ft of actual linear length.
• Copper Development Association, The Copper Tube Handbook, Table 14.2e (ACR tube, ASTM B280) - inside diameters of annealed ACR tube: 0.190 in. for 1/4, 0.248 for 5/16, 0.311 for 3/8 and 0.436 for 1/2 in. OD.
• CoolProp 8.0.0 refrigerant property library - saturated liquid density for R-410A, R-22, R-32 and R-454B, the same library behind the BuildSolver PT chart. Checked against the Honeywell Genetron chart at 80°F and the Chemours Opteon XL41 tables at 100°F.
• Pioneer, Refrigerant Piping Specs - published mini-split rates per foot past 25 ft, read on October 12, 2026. R-454B on a 1/4 in. liquid line: 0.11 oz for the WYT-20U, WYT-20S, WYT-24, WYT-25, CYT-24, UYT-24 and RYT-24 series, 0.16 oz for CYK-24 and FYB-24. R-454B on a 3/8 in. liquid line: 0.32 oz for CYB-20, UYB-20 and RYB-20. R-32 on a 1/4 in. liquid line: 0.11 oz for WYT-17 and WYT-FA. The low-rate warning names the lowest published rate it has for the line and refrigerant you pick, from this and the manuals below. These are a few makers' rates, not a complete list, so the warning says only that a rate below the lowest of them, or a low rate where the list has none for the line and refrigerant, may be a typo.
• Gree, FLEXX36HP230V1AO / FLEXX60HP230V1AO installation and owner's manual (outdoor unit) - R-410A inverter units on a 3/8 in. liquid line (FLEXX36HP230V1AO and FLEXX60HP230V1AO). The additional refrigerant amount for extra pipe is printed as .32 oz/ft (30g/m), beside a standard pipe length of 25 ft and no added charge up to 31 ft.
• Midea, Breezeless E R32 3D Inverter technical manual, document TM_CB1(GA)_R32_3D INV_EU_NA_2501 - the 24k unit on a 3/8 in. liquid line with "24g/m (0.26oz/ft)" of R-32 past the factory length.
• Panasonic, CS/CU-Z25UFEA-1 and Z35UFEA-1 service manual (order no. PAPAMY1807103CE, copy hosted by a retailer) - R-32 on a 1/4 in. liquid line with an additional gas amount printed as 10 g/m and 0.1 oz/ft, past 7.5 m, which is 24.6 ft.
• UL 60335-2-40 - the safety standard for A2L heat pumps and air conditioners, which ties the total refrigerant charge to the space served. Referenced only, this page does not calculate that limit.
• Manufacturer's installation instructions - the charge rate, the factory length, the long-line limits and the final charging method for the unit on the job.

Limitations of this calculator

• The result is only as right as the rate and factory length you enter, so take both from the installation instructions that shipped with the outdoor unit you are setting today.
• The addition is a starting amount. Manufacturers call for a final charge check after it, by subcooling, superheat or weight, and that procedure governs.
• The reference estimate assumes the liquid line runs full of liquid at the temperature you enter and treats subcooled liquid as saturated liquid at that temperature, which reads about half a percent light for every 10°F of subcooling. It ignores the suction line, the oil dissolved in the refrigerant and anything held in an accumulator or receiver.
• Line set sizing, oil return, traps and long-line accessories are not calculated. Past the length the standard instructions cover, the manufacturer's long-line guide applies.
• For A2L refrigerants (R-454B, R-32) the total charge limit under UL 60335-2-40, the room area it implies and any leak detection requirement are not calculated. Read them from the installation manual.
• When the line is shorter than the factory length, the page prints no number. The short-line instructions in the manual govern that case.
• The work is for a certified technician under EPA Section 608. The calculator gives a preliminary number, and the nameplate, the installation instructions and the local code come first.

Common line set charge mistakes

1. Using equivalent length for the charge. Equivalent length adds allowances for elbows and is how manufacturers judge whether a long line is acceptable. Goodman's guide bases the charge addition on actual linear length. Measure the tubing, not the fitting count.
2. Carrying an R-410A rate to an A2L unit. R-454B and R-32 have different liquid densities and different factory charges. A rate from an R-410A manual does not transfer. The form clears the rate when you change refrigerant for this reason.
3. Treating the physical estimate as the rate. The liquid in 3/8 in. R-410A line at 100°F is about 0.52 oz per foot, below Goodman's 0.6. Charging by the physics alone would leave the system short of what the manufacturer expects.
4. Skipping the final charge check. The addition gets the system close. Close is not finished. Indoor airflow, the actual liquid line temperature and the coil all move the right charge, so finish with the manufacturer's charging method.
5. Forgetting the line already in the factory length. The first part of the run is already paid for. Subtract it before multiplying, or a 50 ft line gets charged as if all 50 ft were extra.

Common questions about line set charge

Related calculators and guides

• Superheat and subcooling calculator The final charge check after the addition.
• Refrigerant PT chart Saturation pressure and temperature for R-410A, R-22, R-32 and R-454B.
• The A2L refrigerant transition R-454B, R-32, listings and leak detection for contractors.
• Replacement AC sizing calculator Load check before a changeout.
• All tools Every public BuildSolver calculator in one list.

Used on the same job

• AC temperature split calculator Delivered capacity from return and supply readings.
• Static pressure calculator Airflow check before trusting a charge reading.
• Condensate drain calculator Drain size and slope for the indoor coil.