Subcooling Calculator

Saturated Liquid Temperature:
Liquid Line Temperature:


About Subcooling Calculator (Formula)

A Subcooling Calculator is a valuable tool used in the field of refrigeration and air conditioning to determine the extent to which a liquid refrigerant is cooled below its saturation temperature at a given pressure. Subcooling is a critical parameter in these systems as it ensures the refrigerant remains in its liquid state before entering the evaporator coil, preventing the risk of flash gas and enhancing system efficiency. This article explores the concept of subcooling, its importance, and the formula used in a Subcooling Calculator.

The Significance of Subcooling:

In a refrigeration cycle, subcooling serves several essential purposes:

  1. Preventing Flash Gas: When liquid refrigerant enters the evaporator coil, it absorbs heat and evaporates. If the liquid is not adequately subcooled, it may partially vaporize prematurely, leading to decreased system efficiency and potential compressor damage.
  2. Improved Efficiency: Subcooling ensures that only liquid enters the evaporator, maximizing heat absorption during the phase change from liquid to vapor. This enhances cooling capacity and overall system efficiency.
  3. Stability: Subcooling helps maintain stable and predictable system performance by ensuring a consistent flow of liquid refrigerant to the evaporator.

The Subcooling Formula:

The subcooling process involves cooling the liquid refrigerant below its saturation temperature while maintaining constant pressure. The formula for calculating subcooling is as follows:

Subcooling (ΔTsub) = Saturation Temperature (Tsat)Actual Liquid Temperature (Tliquid)


  • Subcooling (ΔTsub) is the difference between the saturation temperature and the actual liquid temperature, measured in degrees Celsius (°C) or degrees Fahrenheit (°F).
  • Saturation Temperature (Tsat) is the temperature at which the refrigerant exists as a saturated liquid at a specific pressure, typically found in pressure-temperature tables for the refrigerant being used.
  • Actual Liquid Temperature (Tliquid) is the temperature of the liquid refrigerant at a specific point in the system, measured using a thermometer or temperature sensor.

Using the Subcooling Calculator:

A Subcooling Calculator simplifies the subcooling determination process. To use it, follow these steps:

  1. Identify the Refrigerant: Know the type of refrigerant being used in the system.
  2. Determine the Pressure: Measure or obtain the system’s operating pressure.
  3. Find Saturation Temperature: Refer to a pressure-temperature table for the selected refrigerant to find the saturation temperature at the given pressure.
  4. Measure Liquid Temperature: Use a thermometer or temperature sensor to measure the actual temperature of the liquid refrigerant at a specific point in the system.
  5. Apply the Formula: Input the saturation temperature and the actual liquid temperature into the Subcooling Calculator, and it will provide the subcooling value.


In refrigeration and air conditioning systems, subcooling is a critical parameter for ensuring efficient and stable operation. Utilizing a Subcooling Calculator simplifies the process of calculating subcooling, allowing technicians and engineers to optimize system performance, prevent flash gas issues, and enhance overall efficiency, ultimately contributing to the reliability and effectiveness of refrigeration systems.