Refrigerant Charge Calculator

Summary

Enter your system capacity, base charge, line set length, and pipe diameter to calculate the total refrigerant charge needed.

How it works

1. Enter the manufacturer base charge weight in ounces (found on the unit data plate or installation manual).
2. Enter the factory-rated line set length the base charge was designed for (usually 15–25 ft).
3. Enter the actual liquid line set length installed at the job site in feet.
4. Select the liquid line diameter (3/8 in is most common for residential mini-splits; 3/8 or 1/2 in for central systems).
5. The tool computes the difference in feet and applies the standard oz/ft correction rate for the chosen pipe size.
6. The result shows total charge in ounces and pounds plus ounces, and whether to add or remove refrigerant.

Use cases

• Verify the correct refrigerant amount before commissioning a new mini-split or central AC.
• Calculate refrigerant to add when running a longer-than-standard line set.
• Determine refrigerant to remove when a line set is shorter than the factory-rated length.
• Cross-check field measurements against manufacturer data plate specs.
• Train HVAC apprentices on line-length correction procedures.
• Generate a quick reference for multi-zone mini-split installs with varying line lengths.

Frequently Asked Questions