It is very simple to calculate your usage especially for a home. All you have to do is calculate how many lights , fans & electronic appliances you want to run on HOME UPS after the Power Fails .
For Example if you have a 2 bedroom flat and 3 people staying at home , you may use 1 light and 1 fan each in a hall and one bedroom with 1 TV . so usage would be 2 Lights + 2 Fans + 1 TV .
Approx 2 lights * 50 Watts + 2 Fans * 100Watts + 1 32inch LCD TV * 100Watts = 400Watts
So ,you need to decide on a 800-900VA Home UPS Model which would give you 650Watts of output .
Check out our Power Calculator to estimate your power consumption. Launch Power Calculator