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      12,000 BTU through-the-wall air conditioner

      Midea MT12VB2

      Average efficiency for its size: a CEER of 13.9 ranks #9 of 15 through-the-wall air conditioners.

      It cools a room of about 450-550 sq ft, draws about 863 watts and costs about $117 a year to run at typical U.S. use and prices.

      CEER
      13.9 Combined efficiency, higher is better
      Average · beats 57%
      Cooling
      12,000 BTU/hFor about 450-550 sq ft
      Energy use
      648 kWh/yr46% less than the federal minimum
      Unit size
      24.1" wide 14.7" high, 20.9" deep, 59 lb

      A good fit if…

      • You want the very top tier - it meets the ENERGY STAR Most Efficient criteria.

      Think twice if…

      • You only have ordinary outlets - it needs a 230 V circuit and plug.
      • You also need heat - it cools only.
      • You want to mount it in a window - it needs a wall sleeve.

      Calculate my running costCheck the size for my room

      Details

      Specifications12,000 BTU, 230 V
      General
      BrandMidea
      Also sold asFrigidaire, Brothers, Seasons, PerfectAire, DuraSTAR
      Model numberMT12VB2
      TypeThrough-the-wall
      HeatingNo, cooling only
      CompressorVariable speed (inverter)
      Voltage230 V (needs a 230 V outlet)
      RefrigerantR-32 (GWP 675)
      Support bracket includedNo
      On the market sinceFebruary 10, 2026
      Last certifiedSeptember 29, 2026
      Performance
      Cooling capacity12,000 BTU/h
      CEERCombined energy efficiency ratio, includes standby power13.9
      Yearly energy useENERGY STAR test: 750 hours648 kWh
      Better than federal minimum46% less energy
      ENERGY STAR Most EfficientYes
      Size
      Width × height × depth24.1" W × 14.7" H × 20.9" D
      Weight59 lb
      How it compares with 14 other through-the-wall units#9 of 15
      • CEER (class median 13.9)13.9, tied with 4 others
      • Yearly cost vs. class median ($117)about the same
      • Width 24.1" (class median 26.5")narrower than 64%
      • Weight 59 lb (class median 110 lb)lighter than 71%
      • Rank among 13 similar designs#9

      Compared with the other ENERGY STAR certified through-the-wall units. Yearly cost at 750 hours and 18.0¢/kWh.

      Same unit, other model numbers8

      These model numbers have the same capacity, efficiency, energy use, dimensions and weight as the Midea MT12VB2: the same unit under another brand, or with a colour or retailer code. Everything on this page applies to them.

      Questions7
      How many square feet does the Midea MT12VB2 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 Midea MT12VB2 use?
      About 863 watts at full power (12,000 BTU/h divided by its CEER of 13.9), which is 3.8 amps at 230 V. That is 0 W less than the typical unit in its class (863 W), or $0 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 40% of the 15 units in the class.
      What outlet does the Midea MT12VB2 need?
      It is a 230 V unit that draws 3.8 A, so it needs its own 230 V circuit with a matching plug (typically NEMA 6-15 or 6-20). If the room has only ordinary 115 V outlets, an electrician has to add one. Only 60% of the 15 certified units in this class are 230 V.
      What are the dimensions of the Midea MT12VB2, and will it fit my window?
      24.1" W × 14.7" H × 20.9" D, 59 lb. It is narrower than 64% of its 14 competitors and lighter than 71% of them. It slides into a wall sleeve, so compare the sleeve opening with the unit before buying.
      Can the Midea MT12VB2 also heat the room?
      No, it only cools. If you also need heat, 2 certified units in this class can do both; see the list of air conditioners with heat.
      Is the Midea MT12VB2 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 $117, so it saves roughly $64 a year.
      Is the Midea MT12VB2 the same as the Midea MAT12R2FWTK?
      As far as the certified data goes, yes. ENERGY STAR lists 9 model numbers with the same capacity, efficiency, energy use, dimensions and weight, which means the same unit sold under another brand or with a different colour or retailer code. The full list is on this page.

      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 Midea MT12VB2
      2. How you use it
      Per year
      $182
      Per month of use
      $33
      Per day
      $1.11
      Per hour
      13.8¢
      Power draw
      863 W

      Electricity used: 1,140 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 Midea MT12VB2.

      ModelCEERCompared with this one
      Friedrich WCVT12B30A13.9same CEER, 2.4" wider, 51 lb heavier
      Wallmaster WCVT12B30B13.9same CEER, 2.4" wider, 51 lb heavier
      Midea MAT14R2FWTK13.9same CEER, 4 lb heavier
      Midea MT10VB214.10.2 CEER higher
      Friedrich WCVT10B10B14.20.3 CEER higher, 2.4" wider, 51 lb heavier, 115 V

      See all 15 through-the-wall air conditioners, ranked

      Source: ENERGY STAR Certified Room Air Conditioners (U.S. EPA), certification of September 29, 2026. How we use the data.