As summer heats up, many homeowners wonder if their portable generator can handle the load of running an air conditioning (A/C) unit. The short answer is yes, but it's essential to understand the nuances of power requirements and proper setup.

Understanding Power Requirements

Air conditioners have two critical power ratings: starting watts and running watts.

  1. Starting Watts: When an A/C unit first turns on, it requires a surge of power to get the compressor and fan motor running. This initial burst, known as inrush current, can be two to three times higher than the unit’s normal operating power. For example, a typical 10,000 BTU window A/C might need around 2200-3000 starting watts.

  2. Running Watts: After the initial surge, the A/C settles into its normal operating mode, consuming less power. The same 10,000 BTU unit might run continuously on about 1200 watts.

Generator Sizing

To ensure your generator can handle your A/C, you need to select one that can provide enough starting watts. If your A/C requires 3000 starting watts, you'll need a generator rated for at least that much, plus any other appliances you plan to run simultaneously. For a margin of safety, consider a generator with a slightly higher capacity than your calculated needs.

Using a Soft Start Capacitor

A useful device that can help is a soft start capacitor. This component reduces the inrush current required to start the A/C by slowly ramping up the power, rather than demanding a massive surge all at once. By installing a soft start capacitor, you can significantly lower the starting wattage requirement of your A/C unit. This means your generator doesn’t need to be as powerful, making it more feasible to run the A/C efficiently.

Practical Tips

  1. Check Your A/C Specs: Look at the label on your A/C unit to determine the exact starting and running wattage requirements.

  2. Match Generator Capacity: Ensure your generator can handle the combined starting watts of all appliances you wish to run, including the A/C.

  3. Consider Soft Start Technology: Investing in a soft start capacitor can make your setup more efficient and reduce the strain on your generator.


In conclusion, while a portable generator can run an A/C unit, it's crucial to understand the power demands and use appropriate technology to manage those demands. By carefully selecting your generator and considering a soft start capacitor, you can stay cool even during a power outage.