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      12,000 BTU U-shaped window air conditioner

      Whirlpool WHAW121INV

      Very good efficiency for its size: a CEER of 16.0 ranks #9 of 34 12,000 BTU window air conditioners.

      It cools a room of about 450-550 sq ft, draws about 750 watts and costs about $101 a year to run at typical U.S. use and prices.

      CEER
      16.0 Combined efficiency, higher is better
      Very good · beats 82%
      Cooling
      12,000 BTU/hFor about 450-550 sq ft
      Energy use
      563 kWh/yr47% less than the federal minimum
      Unit size
      24.2" wide 14.5" high, 20.3" deep, 58 lb

      A good fit if…

      • You want low bills - its CEER beats 82% of 12,000 BTU window air conditioners.
      • You want a quieter room and a usable window - the window closes into the U, so the compressor sits outside the glass.
      • You want to plug it into an ordinary outlet - it runs on 115 V.
      • You want the very top tier - it meets the ENERGY STAR Most Efficient criteria.

      Think twice if…

      • You also need heat - it cools only.

      Calculate my running costCheck the size for my room

      Details

      Specifications12,000 BTU, 115 V
      General
      BrandWhirlpool
      Model numberWHAW121INV
      TypeWindow
      DesignU-shaped (window closes through it)
      HeatingNo, cooling only
      CompressorVariable speed (inverter)
      Voltage115 V (standard outlet)
      RefrigerantR-32 (GWP 675)
      Support bracket includedYes
      On the market sinceSeptember 30, 2026
      Last certifiedSeptember 30, 2026
      Performance
      Cooling capacity12,000 BTU/h
      CEERCombined energy efficiency ratio, includes standby power16.0
      Yearly energy useENERGY STAR test: 750 hours563 kWh
      Better than federal minimum47% less energy
      ENERGY STAR Most EfficientYes
      Size
      Width × height × depth24.2" W × 14.5" H × 20.3" D
      Weight58 lb
      How it compares with 33 other 12,000 BTU window units#9 of 34
      • CEER (class median 15.0)16.0, tied with 7 others
      • Yearly cost vs. class median ($108)$7 less
      • Width 24.2" (class median 20.3")narrower than 21%
      • Weight 58 lb (class median 59 lb)lighter than 55%
      • Rank among 12 similar designs (U-shaped)#3

      Compared with the other ENERGY STAR certified 12,000 BTU window units. Yearly cost at 750 hours and 18.0¢/kWh.

      Questions7
      How many square feet does the Whirlpool WHAW121INV cool?
      At 12,000 BTU/h it suits a room of about 450 to 550 sq ft with normal sun and two people, following the ENERGY STAR sizing guide. In a heavily shaded room that stretches to about 495-605 sq ft; in a very sunny one it shrinks to 405-495 sq ft. A kitchen needs 4,000 BTU more.
      How many watts and amps does the Whirlpool WHAW121INV use?
      About 750 watts at full power (12,000 BTU/h divided by its CEER of 16.0), which is 6.5 amps at 115 V. That is 50 W less than the typical unit in its class (800 W), or $7 a year cheaper to run at 18.0¢/kWh. Its inverter compressor slows down instead of cycling, so real use is usually lower. Its CEER beats 71% of the 34 units in the class.
      Can the Whirlpool WHAW121INV run on a standard outlet?
      Yes. It runs on 115 V and draws about 6.5 A, well inside a standard 15 A outlet, but do not share the circuit with a space heater, microwave or other big load. 12% of certified units in this class need 230 V, so a 115 V model is the easy case.
      What are the dimensions of the Whirlpool WHAW121INV, and will it fit my window?
      24.2" W × 14.5" H × 20.3" D, 58 lb. It is narrower than 21% of its 33 competitors and lighter than 55% of them. The window closes into the U-shaped slot, so measure the opening height as well as the width: you need at least the unit's 24.2" width between the frame sides.
      Is the Whirlpool WHAW121INV U-shaped design an advantage?
      Mostly yes. The sash closes into the unit, so the window stays sealed and daylight comes in, and the compressor is outside the glass, which cuts noise indoors. The trade-off is a window that must slide up and down, and a few extra steps to fit the foam seals.
      Can the Whirlpool WHAW121INV also heat the room?
      No, it only cools. If you also need heat, 5 certified units in this class can do both; see the list of air conditioners with heat.
      Is the Whirlpool WHAW121INV worth buying to replace an old air conditioner?
      An old unit of the same size at 9 CEER would cost about $180 a year to run at 750 hours and 18.0¢/kWh; this one costs about $101, so it saves roughly $79 a year.

      Running cost calculator

      Pre-filled with this model. Pick your state and how many hours you run it, or see the yearly cost in every state.

      1. The air conditioner Whirlpool WHAW121INV
      2. How you use it
      Per year
      $158
      Per month of use
      $29
      Per day
      $0.96
      Per hour
      12.0¢
      Power draw
      750 W

      Electricity used: 990 kWh a yearAn old 9 CEER unit of the same size would cost $282

      Power draw is capacity divided by CEER, which already includes standby power. Inverter units often run below full power, so real use can be lower. Electricity prices: U.S. EIA residential averages (12 months to July 2026). Days a year start from your state's cooling degree days (NOAA 1991-2020 normals).

      Closest alternatives

      Units with a similar CEER in the same class, and what sets each one apart from the Whirlpool WHAW121INV.

      ModelCEERCompared with this one
      Midea MAW12V1WBK16.0same CEER, 2.5" narrower, 5 lb lighter, standard box
      Kühl KCVS12B10B16.20.2 CEER higher, 1.7" wider, 52 lb heavier, saddle design
      Frigidaire Gallery GHWW125TF116.0same CEER, 5" narrower, standard box
      Midea MAW12U1KWT-M16.0same CEER, 5" narrower, saddle design
      Midea MWEUWA-12CRFN8-BCP016.0same CEER, 5.1" narrower, 8 lb lighter, standard box

      See all 34 12,000 BTU window air conditioners, ranked

      Source: ENERGY STAR Certified Room Air Conditioners (U.S. EPA), certification of September 30, 2026. How we use the data.