How this calculator works
The refrigerant charge estimator calculates the mass of refrigerant (kg) held in liquid lines for 12 common refrigerants across 12 copper pipe sizes (¼" to 3⅛" Type-L ASTM B280). Liquid-line mass = pipe internal volume (m³) × saturated-liquid density (kg/m³). Saturated-liquid densities are sourced from NIST REFPROP 10.0 at the entered liquid-line temperature (default: condensing temperature − 5 K subcooling). The tool calculates pipe internal area from ASTM B280 Type-L nominal OD and wall thickness, then multiplies by entered line length. For A2L refrigerants (R-32, R-454A, R-454B, R-454C, R-455A) the estimated charge is compared against the IEC 60335-2-89:2019 room-area limit — a flag is raised if the charge may exceed the leakable limit for the entered room. This is an estimation tool; actual charge on a commissioned system should be verified by weigh-in method per EN 378-2.
References: NIST REFPROP 10.0; ASTM B280-20; IEC 60335-2-89:2019; ASHRAE 15-2019 (refrigerant safety).