EER to COP Conversion
Enter your known values, leave one input blank, and solves for the missing one. Try different units for next level excitement!
Learning zone
The two numbers describe identical hardware; only the bookkeeping differs. COP is watts out per watt in — clean, dimensionless, and what the rest of the world quotes. EER divides BTU/hr out by watts in, which leaves the conversion factor 3,600/1,055.06 = 3.412 stranded inside the ratio. Multiply COP by 3.412 to get EER, divide to go back.
Useful landmarks: a minimum-efficiency US split system at EER 11 is COP 3.22; a good variable-speed machine at EER 14 is COP 4.10; a water-cooled chiller at 0.5 kW/ton corresponds to EER 24 and COP 7.0. The trap is arithmetic drift — 3.412 is often rounded to 3.41 or even 3.4, which shifts a COP-to-EER conversion by up to a third of a point, enough to move a piece of equipment across a rebate threshold. Worked example: COP 3.0 × 3.412 = EER 10.24; going the other way, a SEER-13 nameplate implies roughly COP 3.81 at its rating point.
- = Energy efficiency ratio
- = Coefficient of performance
- Energy efficiency ratio — Energy Efficiency Ratio (EER), Fin Heat Transfer Rate
- Coefficient of performance — Coefficient of Performance (COP), Minor Loss from K Factor