Superheat & Subcooling Calculator

Calculate superheat and subcooling for R-410A, R-22, and R-404A systems. Enter line pressure and actual temperature to get your reading.

Refrigerant

Suction Line Pressure (PSI)

Actual Suction Line Temperature (°F)

Superheat

0.0°

Enter values above and click calculate.

How It Works

Superheat and subcooling are two of the most important measurements when diagnosing a refrigeration or AC system. They tell you whether the refrigerant charge is correct and whether the system is operating efficiently.

Superheat

Superheat (°F) = Actual Suction Temp − Saturated Suction Temp

Superheat is measured on the low side (suction line). The saturated suction temperature is looked up from the pressure using a PT chart. A positive superheat means the refrigerant has absorbed enough heat to fully vaporize before reaching the compressor.

Subcooling

Subcooling (°F) = Saturated Liquid Temp − Actual Liquid Line Temp

Subcooling is measured on the high side (liquid line). It tells you how much the liquid refrigerant has cooled below its condensing temperature. Proper subcooling ensures solid liquid refrigerant reaches the metering device.

Target Ranges

Superheat: Typically 8–18°F for residential TXV systems, 10–25°F for fixed orifice systems.
Subcooling: Typically 10–18°F for TXV systems, 5–10°F for fixed orifice systems.