Refrigerant Line Charge Calculator
Calculate the amount of refrigerant needed to charge the lines in a split cooling system by entering the size and length of the lines below.
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Joe is the creator of Inch Calculator and has over 20 years of experience in engineering and construction. He holds several degrees and certifications.
How to Calculate How Much Charge is Needed For a Split-System Air Conditioners and Heat Pumps
When charging a system there are a few components that need to be accounted for when estimating the amount of refrigerant needed. The manufacturer of the equipment being charged will provide specs for the amount of refrigerant to add to the system and the manual should be consulted for that information.
However, this leaves the liquid and suction lines between the units unaccounted for. The length of those lines will need to be accounted for to avoid under or over-charging the system.
To more accurately approximate the amount of charge needed, add the amount recommended by the manufacturer with the amount needed for the refrigerant lines.
Estimating Charge Needed for Refrigerant Lines
To calculate the refrigerant needed for the lines, start by noting the size of the liquid and suction lines.
Then, consult the table below to find the charge weight needed per foot of lines. Note that the amount of charge will be very different for the liquid and suction lines, and they should be added together to find the total weight per foot.
Finally, multiply the length of the lines in feet by the weight per foot to find the total charge needed. Note that you might need to convert from ounces to pounds at this point.
Charge Needed per Foot of Line
The tables below show the amount of charge needed per foot of line, for various line sizes. Always double-check your charge rates with those recommended or required by the manufacturer of the charge, equipment, and piping in use.
R-410A Refrigerant
| Liquid Line | Suction Line | ||
|---|---|---|---|
| Line Size (OD) | Charge per Foot | Line Size (OD) | Charge per Foot |
| 1/4″ | 0.19 oz/ft | 1/2″ | 0.04 oz/ft |
| 5/16″ | 0.33 oz/ft | 5/8″ | 0.06 oz/ft |
| 3/8″ | 0.51 oz/ft | 3/4″ | 0.09 oz/ft |
| 1/2″ | 1.01 oz/ft | 7/8″ | 0.12 oz/ft |
| 5/8″ | 1.64 oz/ft | 1-1/8″ | 0.2 oz/ft |
| 3/4″ | 2.46 oz/ft | 1-3/8″ | 0.31 oz/ft |
| 7/8″ | 3.27 oz/ft | 1-5/8″ | 0.43 oz/ft |
| 1-1/8″ | 5.58 oz/ft | 2-1/8″ | 0.76 oz/ft |
| 2-5/8″ | 1.17 oz/ft | ||
R-22 Refrigerant
| Liquid Line | Suction Line | ||
|---|---|---|---|
| Line Size (OD) | Charge per Foot | Line Size (OD) | Charge per Foot |
| 1/4″ | 0.23 oz/ft | 1/2″ | 0.02 oz/ft |
| 5/16″ | 0.4 oz/ft | 5/8″ | 0.04 oz/ft |
| 3/8″ | 0.62 oz/ft | 3/4″ | 0.06 oz/ft |
| 1/2″ | 1.12 oz/ft | 7/8″ | 0.08 oz/ft |
| 5/8″ | 1.81 oz/ft | 1-1/8″ | 0.14 oz/ft |
| 3/4″ | 2.688 oz/ft | 1-3/8″ | 0.21 oz/ft |
| 7/8″ | 3.78 oz/ft | 1-5/8″ | 0.3 oz/ft |
| 1-1/8″ | 6.46 oz/ft | 2-1/8″ | 0.53 oz/ft |
| 2-5/8″ | 0.81 oz/ft | ||
You might also be interested in our BTU heating calculator.