The following information is only an approximation, since different brands and models of tools and appliances power usages vary. However the following list is useful in helping you determine the size generator or alternate power system you need.
Remember that every appliance that is plugged in may consume energy even if it is not turned on. For example, TVs, computers, VCRs, and other electronic devices use energy to stay in standby mode. Even your mobile charger for your phone or iPod consumes about 4 watts of electricity per hour.
Electricity is measured in kilowatts. One kilowatt equals 1000 watts, and one thousand watt-hours (one thousand watts used for an hour) mean one kilowatt-hour (1kwh) or one kilowatt used over one hour. Your utility bills show kilowatt-hour usage. The following chart shows the approximate wattage use for the following appliances for one hour
If you look on the nameplates located on many tools and appliances, they will tell you the exact voltage that they draw. Another method is to measure the amperage draw with an ammeter. You can usually find these at your local hardware store. Remember that the starting voltage on an electric motor is higher than the voltage to keep it running.
If you are thinking about running a computer or other sensitive electronics with your generator be aware that running home computers from a standard generator is not advisable. It requires a generator that utilizes AVR (automatic voltage regulation such as the Briggs Pro Max 6000A or an Inverter such as the Honda EU & EM. The other alternative is to use an Uninterpretable Power Supply (UPS). These are typically sold for use with computers to prevent data loss in the event of a power cut.