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The short answer: a portable air conditioner draws about 700 to 1,600 watts while the compressor is running — roughly 6 to 14 amps at 115 volts. As a rule of thumb it is about 115 watts per 1,000 BTU of SACC capacity. An 8,000 BTU SACC unit sits near 950 watts, a 12,000 BTU unit near 1,350. In fan-only mode the same machine drops to 60 to 130 watts. Running 8 hours at 1,200 watts costs about $1.68 at the US average rate of 17.5 cents per kWh.
We do not physically handle the units we rank; our picks come from aggregated owner reviews and expert consensus, explained in how we rank. Model-level recommendations are in best portable air conditioner.
What is the wattage for my size unit?
Match on the SACC figure, not the larger ASHRAE BTU number on the front of the box. Since 2019 the Department of Energy has required portables to be rated by seasonally adjusted cooling capacity, a figure set out in the federal test procedure, which accounts for the hot air that leaks back into a room when a single-hose unit exhausts. A unit advertised as 14,000 BTU ASHRAE is frequently 8,500 to 10,000 BTU SACC, and the wattage tracks the real capacity.
| SACC rating | Running watts | Amps at 115 V | Cost per 8 hours at 17.5¢ | Room size |
|---|---|---|---|---|
| 6,000 BTU | 650 – 800 W | 5.7 – 7.0 A | $0.91 – $1.12 | Up to 250 sq ft |
| 8,000 BTU | 850 – 1,050 W | 7.4 – 9.1 A | $1.19 – $1.47 | 250 – 350 sq ft |
| 10,000 BTU | 1,050 – 1,250 W | 9.1 – 10.9 A | $1.47 – $1.75 | 350 – 450 sq ft |
| 12,000 BTU | 1,250 – 1,450 W | 10.9 – 12.6 A | $1.75 – $2.03 | 450 – 550 sq ft |
| 14,000 BTU | 1,400 – 1,650 W | 12.2 – 14.3 A | $1.96 – $2.31 | 550 – 700 sq ft |
| Fan only, any size | 60 – 130 W | 0.5 – 1.1 A | $0.08 – $0.18 | — |
| Heat mode (resistance) | 1,000 – 1,800 W | 8.7 – 15.7 A | $1.40 – $2.52 | — |
How do I find the exact figure for my unit?
Look at the nameplate sticker, usually on the back or the side near the power cord. It lists either rated power in watts or rated current in amps, and it is the manufacturer’s own figure at test conditions. If it gives amps, multiply by 115 to get watts: a label reading 11.0 A means about 1,265 watts.
The label may also show CEER — combined energy efficiency ratio, in BTU per watt-hour. Divide SACC by CEER to get running watts. A 10,000 BTU SACC unit at CEER 8.5 works out to 1,176 watts. That figure is also the honest way to compare portables against window units, which typically rate CEER 11 to 15 and therefore deliver the same cooling on 30 to 50 percent less power.
What circuit does a portable air conditioner need?
Standard 115-volt household power, but with more headroom than most people give it. The National Electrical Code treats any load running three hours or more as continuous and limits it to 80 percent of the branch circuit rating — 12 amps on a 15-amp circuit, 16 amps on a 20-amp circuit. A 12,000 BTU portable at 11 to 12.6 amps is effectively using the entire allowance of a 15-amp bedroom circuit on its own.
- Wall outlet only. No extension cord, no power strip, no surge protector, no timer plug — manufacturers prohibit all of them, and the CPSC warns against running high-draw appliances through extension cords.
- Nothing else heavy on the same circuit. A space heater, a hair dryer or a second AC on the same breaker will trip it, and repeated tripping is a symptom, not a nuisance.
- Watch the receptacle. A plug or outlet that runs warm, discolors, or smells hot indicates a loose connection. Stop using it and have an electrician look at it.
- Do not change breakers or wiring yourself. If the unit needs a dedicated 20-amp circuit, that is licensed electrician work.
How do I cut what it costs to run?
The largest single gain is sealing the window kit properly. A single-hose portable puts the room at negative pressure, so hot outdoor air infiltrates through every gap — including the gaps around the kit panel itself. Foam-tape the perimeter, block the accordion slot on a sliding window kit, and the unit stops fighting its own exhaust. Insulating the exhaust hose with a purpose-made sleeve is the second cheapest improvement, since an uninsulated hose radiates the heat it is meant to be removing straight back into the room.
After that: keep the hose short and straight, clean the intake filter every two weeks in season, close blinds on sun-facing windows, and add a ceiling fan so you can hold a higher setpoint — the Department of Energy puts that at about 4°F with no comfort loss. On venting requirements and the alternatives to a window, see do portable air conditioners have to be vented out a window. If the unit is a stopgap for a failing central system, start with why is my AC running but not cooling.