What Size Generator Do You Need for a Window Air Conditioner?
A window AC is a practical way to keep one room cool during a summer outage. A 10,000 BTU unit runs on about 900 watts but needs roughly three times that to start.
| Appliance | Running / starting W | On its own | With fridge, lights and Wi-Fi |
|---|---|---|---|
| Window AC (10,000 BTU) | 900 / 2,700 | 3,000-watt 10 kW standby | 3,500-watt 10 kW standby |
Smallest portable (by starting watts) and smallest standby generator on natural gas, keeping about 20% headroom.
Tips
- Units with inverter compressors start much more gently; check the label for "inverter".
- Cool one bedroom rather than the whole house; it's the difference between a small and a large generator.
- Start the AC first, before other motor loads, to give it the full starting capacity.
See also the appliance wattage chart and what each generator size can run.