Superheat and subcooling calculator

Calculate target superheat for fixed orifice systems and actual superheat and subcooling from suction and liquid line readings.

What this means

Superheat is how far suction vapor is above its dew point saturation temperature. Subcooling is how far liquid refrigerant is below its bubble point saturation temperature. Compare your readings with the equipment manufacturer's charging instructions, after checking airflow, filters and operating conditions. These numbers alone do not prove a charge problem.

Formula used

  • Target superheat (°F) = (3 × indoor wet bulb − 80 − outdoor dry bulb) ÷ 2
  • Actual superheat (°F) = suction line temperature − dew point saturation temperature
  • Actual subcooling (°F) = bubble point saturation temperature − liquid line temperature
  • Saturation temperatures use linear interpolation in the selected refrigerant PT table

Related tools

Refrigerant PT chart and lookup · Additional refrigerant charge calculator · Interactive psychrometric chart · Total external static pressure check

Estimates based on your inputs. Always verify against the manufacturer's data and the codes that apply where you work.

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