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How many watts does a window air conditioner use?

A typical window air conditioner uses 440–1,250 watts when running and draws 3.7–10.4 amps at 120 volts.

Window air conditioner watts, amps and circuit

Typical power use of a window air conditioner
Running watts440–1,250 W
Voltage120 V
Running amps3.7–10.4 A
Circuitstandard 120 V outlet

Also called: window ac, window unit, air conditioner, room air conditioner, small window ac.

Window air conditioner watts by size and type

Running and starting watts of window air conditioner types
Size or typeRunning watts, WVolts, VAmps, AStarting watts, W
Window air conditioner440–1,2501203.7–10.4—
5,000 BTU440–4551203.7–3.8—
6,000 BTU495–5351204.1–4.5—
8,000 BTU660–6951205.5–5.8—
10,000 BTU865–8701207.2–7.3—
12,000 BTU1,030–1,0601208.6–8.8—
14,000 BTU1,25012010.4—
05001,0001,500Watts, WSize or typeWindow airconditionerWindow air conditioner, Running watts: 440–1,250440–1,2505,000 BTU5,000 BTU, Running watts: 440–455440–4556,000 BTU6,000 BTU, Running watts: 495–535495–5358,000 BTU8,000 BTU, Running watts: 660–695660–69510,000 BTU10,000 BTU, Running watts: 865–870865–87012,000 BTU12,000 BTU, Running watts: 1,030–1,0601,030–1,06014,000 BTU14,000 BTU, Running watts: 1,2501,25002505007501,0001,250Watts, WSize or typeWindow air conditionerWindow air conditioner, Running watts: 440–1,250440–1,2505,000 BTU5,000 BTU, Running watts: 440–455440–4556,000 BTU6,000 BTU, Running watts: 495–535495–5358,000 BTU8,000 BTU, Running watts: 660–695660–69510,000 BTU10,000 BTU, Running watts: 865–870865–87012,000 BTU12,000 BTU, Running watts: 1,030–1,0601,030–1,06014,000 BTU14,000 BTU, Running watts: 1,2501,250
Watts of window air conditioner types. The lighter part of a bar is the upper end of the typical range.

What size generator runs a window air conditioner?

A window air conditioner needs a generator that supplies at least 1,250 running watts. Starting a window air conditioner takes a short surge of several times its running watts, and the surge is not listed here: size the generator from the locked-rotor amps (LRA) on the nameplate or the maker's generator guidance, not from the running watts.

How long a portable power station runs a window air conditioner

Runtime of a window air conditioner on a portable power station, at 85% inverter efficiency
Battery capacity, WhAt 1,250 W, hAt 440 W, h
5000.31
1,0000.71.9
2,0001.43.9
3,6002.47

A 500 Wh portable power station runs a window air conditioner drawing 1,250 W for about 0.3 hours at 85% inverter efficiency. Runtime = capacity × 85% ÷ watts; the 85% efficiency is an assumption. The power station's AC output must be at least 1,250 W.

What it costs to run a window air conditioner

Running a window air conditioner at 845 W, the middle of its 440–1,250 W range, for one hour a day uses 308.4 kWh a year. That costs about $56 a year at $0.18 per kWh, the US average residential price for August 2026.

W
h
$/kWh

Your bill's total ÷ kWh used. 0.18 is the US residential average.

Result
$4.63 / month
Per day
$0.15
Per year
$56
Energy per day
0.85 kWh
Energy per month
25.7 kWh

How it is calculated

  1. kWh per day = 845 W × 1 h ÷ 1,000 = 0.845
  2. Per month = 0.845 kWh × 30.4 days × $0.18 = $4.63

What affects window air conditioner power use

Cooling capacity in BTU and the efficiency rating set the running watts. The rows are the cooling watts GE and Frigidaire list for their 115 V window units. The compressor cycles with the thermostat and needs a short surge to start, which matters on a generator or inverter. The largest window units are made for 240 V outlets; check the plug and nameplate before choosing an outlet.

How the amps are calculated

Amps = watts ÷ volts. For 1,250 W at 120 V that is 10.4 A. The 440–1,250 W range covers typical models; the nameplate on a window air conditioner gives the exact figure.

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