Refrigeration COP Calculator
Find the coefficient of performance (COP) of a refrigeration system or heat pump from its cooling duty and compressor power. Enter the cooling capacity and the electrical/mechanical power the compressor draws, and the calculator returns the cooling COP, the heat-pump (heating) COP and the total heat rejected at the condenser.
Enter Values
How to use this calculator
- Enter the cooling capacity Qc in kW — the useful heat the system removes from the cold space.
- Enter the compressor power input W in kW — the work put into the compressor.
- Read the cooling COP, the heating COP if the machine is run as a heat pump, and the heat rejected Qh.
How it works
COP measures how much useful heat you move per unit of work. In cooling mode, COP = Qc / W. By energy balance, everything absorbed plus the compressor work must leave at the condenser, so the heat rejected is Qh = Qc + W. Running the same cycle as a heat pump, the useful output is Qh, giving a heating COP of (Qc + W) / W, which is always exactly one greater than the cooling COP.
Worked example
Worked example. A chiller removes 5 kW while its compressor draws 1.25 kW. Cooling COP = 5 / 1.25 = 4. As a heat pump the heating COP would be 4 + 1 = 5, and the heat rejected at the condenser is Qh = 5 + 1.25 = 6.25 kW.
Common mistakes
- Mixing units — Qc and W must both be in the same unit (both kW here), or the ratio is wrong.
- Expecting COP to be less than 1. Because it moves heat rather than creating it, COP is normally well above 1.
- Forgetting that heating COP is always cooling COP + 1, not a separately measured figure for the same machine.
Frequently asked questions
Why is heating COP always one higher than cooling COP?
In heating mode the useful output is the heat rejected at the condenser, Qh = Qc + W. Dividing by the same work W gives (Qc + W)/W = Qc/W + 1, so the heating COP is exactly one more than the cooling COP.
What makes COP go down in practice?
A bigger temperature lift — a hotter condenser or colder evaporator — forces the compressor to do more work for the same cooling, so COP drops. That is why a fridge in a hot room, or a heat pump on a very cold day, performs worse.
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Tip: Enter any known values to calculate the remaining results.
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