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      What size portable air conditioner do I need?

      Enter your room. The answer is in SACC, the cooling a portable unit really delivers, and links straight to the most efficient units in that size.

      You need about 7,000 BTU (SACC)See 8,000 BTU models →
      Your room
      Real cooling needed
      7,000 BTU (SACC)
      Buy this size class
      8,000 BTU

      Most efficient in that size: Hisense HIAP0825TWD (13.5 CEER)

      ENERGY STAR floor-area guide applied to SACC: the table value for the floor area, 10% less for a heavily shaded room, 10% more for a very sunny one, 600 BTU per person beyond two and 4,000 BTU for a kitchen. Compare it with the SACC (not the box number) of the unit you are considering.

      Portable AC size chart

      Room sizeReal cooling (SACC)Models
      100-150 sq ft5,000 BTU5,000 BTU and under
      150-250 sq ft6,000 BTU6,000 BTU
      250-300 sq ft7,000 BTU8,000 BTU
      300-350 sq ft8,000 BTU8,000 BTU
      350-400 sq ft9,000 BTU10,000 BTU
      400-450 sq ft10,000 BTU10,000 BTU
      450-550 sq ft12,000 BTU12,000 BTU and up
      550-700 sq ft14,000 BTU12,000 BTU and up

      Source: ENERGY STAR room air conditioner sizing guide, normal sun, two people, applied to the SACC of portable units. Rooms over about 600 sq ft are beyond what any certified portable unit delivers.

      Common questions

      Questions7
      What size portable air conditioner for 150 sq ft?
      About 5,000 BTU of real cooling (SACC) with normal sun and two people, following the ENERGY STAR floor-area table. Use about 4500 BTU if the room is heavily shaded and 5500 BTU if it is very sunny. Look at the SACC on the unit's EnergyGuide label or spec sheet, not the larger BTU printed on the box.
      What size portable air conditioner for 250 sq ft?
      About 6,000 BTU of real cooling (SACC) with normal sun and two people, following the ENERGY STAR floor-area table. Use about 5400 BTU if the room is heavily shaded and 6600 BTU if it is very sunny. Look at the SACC on the unit's EnergyGuide label or spec sheet, not the larger BTU printed on the box.
      What size portable air conditioner for 350 sq ft?
      About 8,000 BTU of real cooling (SACC) with normal sun and two people, following the ENERGY STAR floor-area table. Use about 7200 BTU if the room is heavily shaded and 8800 BTU if it is very sunny. Look at the SACC on the unit's EnergyGuide label or spec sheet, not the larger BTU printed on the box.
      What size portable air conditioner for 450 sq ft?
      About 10,000 BTU of real cooling (SACC) with normal sun and two people, following the ENERGY STAR floor-area table. Use about 9000 BTU if the room is heavily shaded and 11000 BTU if it is very sunny. Look at the SACC on the unit's EnergyGuide label or spec sheet, not the larger BTU printed on the box.
      What size portable air conditioner for 550 sq ft?
      About 12,000 BTU of real cooling (SACC) with normal sun and two people, following the ENERGY STAR floor-area table. Use about 10800 BTU if the room is heavily shaded and 13200 BTU if it is very sunny. Look at the SACC on the unit's EnergyGuide label or spec sheet, not the larger BTU printed on the box.
      Why is the SACC lower than the BTU on the box?
      The box usually shows the older ASHRAE rating, measured without the heat a portable unit lets back into the room through its hose and case and the warm air a single-hose unit pulls in. The Department of Energy rating, SACC, subtracts those losses, so it is what the unit really delivers.
      What happens if a portable air conditioner is too big?
      It cools the air quickly and shuts off before it has removed much moisture, so the room feels cold and clammy, and the frequent cycling wastes energy. Inverter units handle a slightly oversized room better, but the right size still works best.

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