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What size generator for a house


When sizing a generator for your house add up all the appliances in your household this will give you the total approximate wattage required to run your house, keep in mind that all the appliances will not be used at once. Once you have approximated the wattage lets covert to kVA for your generator size.

To convert watts to kVA, you can use the formula:


For a common rule of thumb is to use a power factor of 0.8 for general household appliances when specific information is not available

Click here: Watts to kVA calculator

 Wattage Estimation Table:

Appliance  Running Watts
Air conditioner Large wall 3500
Air conditioner small window 2300
Refrigerator 100-800
Microwave Oven 600-1200
Dishwasher 1200-1500
Clothes Dryer 2000-6000
Washing Machine 500-6000
Tv LCD 50-150
Tv LED  30-100
Plasma 200-400
Computer Laptop 20-50
Computer Desktop 100-800
Electric Oven  2000-5000
Toaster 800-1500
Coffee Maker 600-1200
Electric Kettle 1200-2400
Ceiling Fan 10-120
Vacuum Clearner 500-1500
Space Heater 1000-2400
Water Heater(Tank) 3000-4500
Iron 1000-1800
Light Bulbs 20-40


The above wattages are for reference only giving approximations guide only, for best please check the data plate or manual on your appliances for exact running and start wattage. look online for the information or use a wattage meter to get the right starting & running wattage amount. If all seem too hard consult your local electrician. 

Your generators load should not be more than 80% of the generators capacity, so not overloading. 

Feel free to call one of our specialist a call to assist in sizing the right generator. 

Phone: 1800 436 372  Syd: 02 8005 6040 Mel: 03 9013 4400  Bris: 07 3102 5700

Click here for: Home Generators

Case Study: Home Backup

Appliance  Running Wattage Starting Wattage
Refrigerator 700 1400
Microwave Oven 800 1050
Tv 250 250
Computer Laptop 50 50
Computer Desktop 300 300
Electric Oven  1600 1600
Coffee Maker 1200 1200
Ceiling Fan 80 80
Water Heater(Tank) 2400 2400
Lights 200 200
Totals: 7580 8530


Listed above are the appliances typically used in a power outage.

On the Starting Wattage column has a total of 8530 watts if all the appliances are use on startup. On the Running column is the wattage used when running 7580 watts. By not using all the appliances at once this will reduce the wattage even lower.   In this example you could use a 8kVA or 10 kVA generator.