To determine the size of the generator you need, you should consider the appliances you want to power and add up their wattage. If an appliance has a motor, you will need to calculate the total wattage using the formula: Running Wattage (R) = the wattage listed on the appliance, Starting Wattage (S) = Running Wattage x 3, Total Wattage (R + S) = Running Wattage + Starting Wattage. Once you have a list of the items you want to power and the wattages they need, add the numbers together to figure out what size generator would be right for you. The more appliances you want to use, the bigger generator you will need.

Here are some approximate running wattage for various household appliances and technology:

• Refrigerator/Freezer: 600 - 800
• Electric Range (one element): 2500
• Toaster: 1100 - 1700
• Microwave: 1200
• Hot Plate: 1250
• Coffeemaker: 400 - 800

To add a margin of safety and for future power needs, multiply the kilowatts by 1.25. This is the minimum generator capacity required for your home. For example, if you determine that your minimum generator capacity is 17.5 kilowatts, youll want an 18-22 kilowatt generator to adequately power your home during an outage.

Its important to note that some appliances, such as air conditioners, refrigerators, and sump pumps, draw a lot more wattage at the moment they’re cycling on. These surge watts can throw off your calculations if you don’t account for them.

Consumer Reports recommends not spending more on a portable generator that produces more power than you need for the appliances you want to power.