Subcooling Calculator
Enter the refrigerant type, condenser pressure, and liquid line temperature to calculate subcooling degrees and check system charge status.
System Inputs
Subcooling Result
Enter values and press Calculate.
Saturation Temp
—
Liquid Line Temp
—
Subcooling
—
Typical Subcooling Targets
| Range | Indication |
|---|---|
| < 5°F | Likely undercharged |
| 5 – 10°F | Low — check charge |
| 10 – 20°F | Normal range |
| 21 – 30°F | High — possible overcharge |
| > 30°F | Likely overcharged / restriction |
Always verify with the manufacturer's installation manual for your specific equipment model.
Summary
Enter the refrigerant type, condenser pressure, and liquid line temperature to calculate subcooling degrees and check system charge status.
How it works
- Select your refrigerant type (R-410A, R-22, R-134a, R-32, or R-404A).
- Enter the high-side (condenser outlet / liquid line) pressure in PSIG as read from your manifold gauges.
- Enter the actual liquid line temperature in °F measured with a contact thermometer just downstream of the condenser.
- The tool looks up the saturation temperature for that refrigerant at the entered pressure.
- Subcooling = Saturation Temperature − Liquid Line Temperature.
- A color-coded result shows whether subcooling is low, normal (10–20°F), or high, with a diagnostic note.
Use cases
- Verify refrigerant charge on a residential split-system AC or heat pump during commissioning.
- Diagnose undercharge or overcharge conditions on a service call.
- Cross-check manufacturer target subcooling against field measurements.
- Train HVAC apprentices on proper charging procedures using real pressure/temperature values.
- Quick field calculation without carrying a PT chart booklet.
- Validate a new refrigerant charge after recovering and recharging a system.
Frequently Asked Questions
Last updated: 2026-06-11 ·
Reviewed by Nham Vu