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Ranked by hot-day cooling efficiency only

Cooling efficiency on a 95°F afternoon. A single hot-weather test point, when air conditioners work hardest. Higher is more efficient. This list ranks by that one rating. For the units that hold up best in the cold overall, see the cold-climate picks.

Covers heat pumps sold new today (R-454B and R-32 refrigerant). See older R-410A models · Updated

Showing Ductless, 3.5–4.5 tons (39,000–56,999 Btu/h cooling). What size is my system?

Top 10 by hot-day cooling efficiency only: ductless, 3.5–4.5 tons

Ranked by this one rating, not an overall verdict. Every model here is the same size and type, so the numbers compare directly. Higher is better. One certified pairing per model.
  1. 1KUMXA421ALG3.5 tons · 42,000 Btu/h · DuctlessTop 10%13.8
  2. 2KUSXA421Awith ductless indoor unit KNSCB421ALG3.5 tons · 42,000 Btu/h · DuctlessTop 10%13.5
  3. 3ZRUM048GSS0LG4 tons · 48,000 Btu/h · DuctlessTop 10%13.5
  4. 4GMV-V48WL/NHC-T(U)GreeAlso sold as Tosot TMV-V48WL/NHC-T(U)4 tons · 48,000 Btu/h · DuctlessTop 10%13.5
  5. 5MXZ-SM42NLHZ***Mitsubishi ElectricAlso listed as PUMY-HL42NKMU, MXZ-SM42NLHZ-3.5 tons · 42,000 Btu/h · DuctlessTop 10%13.4
  6. 6MCY-MUB0488HS2P-ULCarrier (sold as Toshiba Carrier)4 tons · 48,000 Btu/h · DuctlessTop 10%13.4
  7. 7KUSXB421Awith ductless indoor unit KNSCB421ALG3.5 tons · 42,000 Btu/h · DuctlessTop 10%13.2
  8. 8KUMXA481ALG4 tons · 48,000 Btu/h · DuctlessTop 10%13.1
  9. 9MXZ-SM48NLHZ***Mitsubishi ElectricAlso listed as PUMY-HL48NKMU, MXZ-SM48NLHZ-4 tons · 48,000 Btu/h · DuctlessTop 10%13.1
  10. 10GWHD(42)ND6MOGreeAlso sold as Tosot TM42H32MO, Kinghome KM42X6O, Tosot TM42D6MO, Tosot TMSCI7H4R42 and 5 more; also listed as MUL42HP230V1R32AO, GS5M42HP230V1MO3.5 tons · 42,000 Btu/h · DuctlessTop 10%13.0

Every ductless, 3.5–4.5 tons model, highest first

Top cold-climate picks, ductless 3.5–4.5 tons

These are certified test ratings, not a recommendation for your home. The right size comes from a load calculation by a contractor.

Want this size class’s full distribution and peer percentiles? Switch to Advanced

What good looks like: ductless, 3.5–4.5 tons

Good is better than half of this size class, great is the top quarter, top is the top 10%. The scale comes from the class’s own ratings.

  • COP at 5°F

    Efficiency on a 5°F day

    How much heat the unit makes from each unit of electricity when it is 5°F outside.

    Good
    2.00+
    Great
    2.06+
    Top 10%
    2.11+

  • HSPF2

    Winter-long heating efficiency

    Heating efficiency over a whole winter, measured with a federal test.

    Good
    10.0+
    Great
    10.6+
    Top 10%
    11.0+

  • SEER2

    Summer-long cooling efficiency

    Cooling efficiency over a whole summer, measured with a federal test.

    Good
    21.1+
    Great
    22.0+
    Top 10%
    23.0+

Next steps

The advanced view adds the all-sizes boards, each qualifier’s peer percentiles, charts of every model in each size class, and the EER2 and heat output boards.

Open the advanced view