Superheat & Subcooling Calculator

Superheat and subcooling are how technicians confirm a system has the correct refrigerant charge. Superheat compares the suction line temperature to the evaporator's saturation temperature; subcooling compares the condensing saturation temperature to the liquid line temperature. This tool does both calculations from your gauge and clamp-meter readings.

Tip: Fixed-orifice systems are charged to target superheat; TXV/EEV systems are charged to target subcooling — use whichever your equipment's metering device calls for.

Superheat

Evaporator Saturation Temp (°F)

From your low-side gauge pressure, or use the PT Chart tool.

Suction Line Temp (°F)

Measured at the evaporator outlet / compressor suction line.

Subcooling

Condensing Saturation Temp (°F)

From your high-side gauge pressure, or use the PT Chart tool.

Liquid Line Temp (°F)

Measured at the condenser outlet / liquid line.

Typical targets: Fixed-orifice systems are charged to a target superheat (commonly 8-15°F, check the manufacturer's charging chart). TXV/EEV systems hold superheat constant by design and are instead charged to a target subcooling (commonly 10-20°F). High superheat can mean low charge or a restriction; high subcooling can mean overcharge; low subcooling can mean undercharge or a restriction in the liquid line.