Real BTU Check

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What a portable AC costs to run, and how loud it is

Updated

Take the watts on the listing, multiply by the hours you run it, and divide by 1,000. That is kWh. Multiply by the rate on your own electric bill. The listed watts are close to the most the unit draws. The compressor cycles off once the room is cool, so real use is usually lower.

kWh at the listed wattage

ModelListed wattskWh for 8 hourskWh for 30 nights of 8 hourskWh for 750 hours
Midea Duo 12,000 BTU1,2009.6288.0900
Whynter ARC-14S1,30010.4312.0975
BLACK+DECKER BPACT14WT1,36510.9327.61,024
Whynter ARC-122DS1,2009.6288.0900
BLACK+DECKER BPACT10WT1,2209.8292.8915
Frigidaire FHPC082AC19707.8232.8728
Midea 8,500 BTU8306.6199.2622

Why 750 hours? That is the number of cooling hours per year the DOE test uses when it works out annual energy use for a portable AC. The Midea 8,500 BTU listing gives 615 kWh per year, close to the 622 kWh from its 830 watts over 750 hours.

Turn kWh into cost

  1. Find your rate on your bill. It is usually shown per kWh.
  2. Multiply it by the kWh in the table. For example, 30 nights on the Midea Duo is 288.0 kWh at most.
  3. Expect less. A unit sized right reaches the set temperature and cycles. An inverter unit like the Duo slows down instead of stopping, which Midea says uses less power than a non-inverter unit.

Sizing affects the bill

ENERGY STAR says an oversized unit cools the room too fast to pull out the humidity, which leaves it cold and clammy. An undersized unit runs flat out all day. Both cost more than a unit matched to the room. That is why the calculator sizes by SACC.

Noise

Whynter's FAQ says most portable units run between 50 and 60 dB, and that the level changes with fan speed and when the compressor kicks on. The listings do not say how far away the numbers were measured, and "as low as" means the quietest setting.

ModelNoise on the listing
Midea Duo 12,000 BTUAs low as 42 dB (maker)
Whynter ARC-14S51 dBA on low (maker)
BLACK+DECKER BPACT14WT54 dB (listing)
Whynter ARC-122DS47 dBA on low (maker)
BLACK+DECKER BPACT10WT54 dB (listing)
Frigidaire FHPC082AC150 dB (listing)
Midea 8,500 BTU52.6 dB, 50 dB at minimum (listing)

The outlet

Whynter says to plug a portable AC straight into a grounded wall outlet on a dedicated circuit, not shared with a fridge, a microwave or a power strip, and warns of tripped breakers, overheating and fire risk otherwise. The picks here draw 830 to 1,365 watts. If you are unsure what else is on that circuit, ask a licensed electrician.

Size your own room with the SACC calculator, or compare all seven picks on the roundup page.