Refrigerant Subcooling Calculator
Enter your refrigerant, liquid line pressure, and liquid line temperature to get an instant subcooling value built for systems with a thermostatic expansion valve (TXV).
- Covers All 8 Stocked Refrigerants
- Built for Field Use
- No Login Required
- Updated for Current A2L Data
How the Subcool Calculator Works
Three steps between you and a verified saturation reading no chart flipping required.
Confirm the system uses a TXV
Subcooling is the correct charging method for thermostatic expansion valve systems, not fixed-orifice.
Enter liquid line pressure and temperature
Read both directly from your gauges and a clamp-on thermometer on the liquid line.
Get an instant subcooling value
The calculator converts pressure to saturation temperature and subtracts your actual liquid line temperature.
Subcooling Charging, Explained in Plain Terms
Subcooling measures how much cooler the liquid refrigerant is than its saturation point and that gap is what tells you if a TXV system is charged correctly.
Why Subcooling (Not Superheat) for TXV Systems
A thermostatic expansion valve actively regulates refrigerant flow to maintain consistent superheat at the evaporator, which makes superheat an unreliable charging indicator on these systems. Subcooling, measured on the liquid line before the TXV, isn't affected by that regulation and gives a stable, accurate charging reference instead.
Reading the Manufacturer's Target Subcooling
Every system has a manufacturer-specified target subcooling value, usually printed on the unit's dataplate or in the installation manual, and it varies by equipment model there's no single universal number. Always confirm the target for the specific unit before adjusting charge based on this calculator's output.
What an Out-of-Range Reading Means
Subcooling below the target range typically points to an undercharge or a restriction upstream of the liquid line, while subcooling above target usually indicates an overcharge. Either condition affects system efficiency and, left uncorrected, can shorten compressor life.
Related Calculators
Frequently Asked Questions
Subcooling measures the liquid line before the metering device and applies to TXV systems. Superheat measures the suction line and applies to fixed-orifice systems.
It varies by manufacturer and model always check the specific unit's dataplate or install manual for its target value rather than using a generic number.
Yes, both A2L refrigerants are included with saturation data checked against current manufacturer specs.
Use the superheat calculator instead fixed-orifice systems are charged by superheat, not subcooling.
Need the Refrigerant to Match?
Every calculator links straight to the in-stock cylinder for that refrigerant.