A good EER rating for a central air conditioner is 11.5 or higher (approximately 11.0 EER2), while an excellent rating is 13+ EER (12.4+ EER2). For window ACs, good is 11+ EER and for ductless mini-splits, good starts at 13 EER. These benchmarks help you quickly evaluate any AC unit and determine whether it's a worthwhile investment or a power-hungry compromise.
Use the charts below to see where any unit falls on the efficiency spectrum.
Central Air Conditioner EER/EER2 Chart
Federal tax credit threshold: 12.0 EER2 (approximately 12.6 old EER). Your central AC must meet this alongside 17.5 SEER2 to qualify for the $600 credit. Most units above the "Very Good" line meet this threshold.
Window Air Conditioner EER/CEER Chart
Window ACs now use CEER (Combined EER) which factors in standby power. The chart below shows both for reference:
Larger window ACs tend to have lower EER ratings because the compressor-to-cabinet ratio is less favorable. This is normal and expected. Always compare within the same capacity class.
Ductless Mini-Split EER Chart
Mini-splits typically achieve the highest EER ratings of any residential cooling equipment:
Multi-zone mini-split systems always have lower EER than single-zone models because multi-zone systems must handle varying loads across multiple indoor units, and the outdoor unit is sized for the total connected capacity rather than the actual simultaneous load.
Portable Air Conditioner EER Chart
Portable ACs are the least efficient cooling option due to exhaust heat, single-hose air loss, and less efficient compressor designs:
Portable AC EER is not comparable to central AC or window unit EER. Portable units must exhaust hot air through a vent hose, and single-hose models create negative pressure that pulls warm air in through gaps. Their true cooling efficiency is significantly lower than the rating suggests. If possible, choose a window unit or mini-split instead.
EER by Brand: Top Central AC Models
Understanding EER in Context
A few rules of thumb for interpreting EER charts:
EER improves less dramatically than SEER between models. A unit might jump from 16 to 22 SEER2 (38% improvement) while only going from 11 to 13 EER2 (18% improvement). The SEER gains come from part-load efficiency; EER gains require genuine full-load engineering improvements.
Higher EER generally correlates with higher price. Each additional EER point typically adds $500-$1,500 to system cost for central ACs. The cost premium for high EER is more modest for mini-splits (roughly $200-$500 per point).
EER drops at temperatures above 95 degrees F. The rated EER is tested at 95 degrees F. At 105 or 115 degrees F, actual efficiency drops further. Units with high rated EER tend to maintain their advantage at extreme temperatures.
Key Takeaways
- Good EER for central ACs: 11.5+ (11.0+ EER2). Excellent: 13+ (12.4+ EER2).
- Good EER for window ACs: 11+ CEER. ENERGY STAR: 12.1+ CEER for most sizes.
- Good EER for mini-splits: 13+. Top single-zone units reach 15-17.
- Portable ACs have the lowest EER (7-10 range) and aren't comparable to other types.
- 12.0 EER2 is required for the federal tax credit alongside 17.5 SEER2.
- Compare within equipment type — don't compare a mini-split EER to a portable AC EER.
- Larger units within a category tend to have lower EER due to engineering constraints.
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