If the wattage isn't given you can still figure it out if you know the voltage and amperage. If you multiply the voltage times the amperage, the result equals the wattage of the appliance or device. For example, the decal on the appliance you want to take overseas doesn't list the wattage but gives the voltage as 120 volts and the amperage is 1.1. To find the wattage of that particular appliance, multiply the voltage 120 times the amperage 1.1, 120X1.1=132 watts. If your devices voltage was 120V and the amperage was .18 then 120x.18 = 21.6 watts.

It is also important to remember not to exceed 95% of any given converter or adapters wattage output. In other words if you have a inverter - converter that supplies 25watts of continuous output then 25x95%=23.75 watts. This is the recommended safe limit that the 25 watt inverter - converter above will handle without being overloaded or damaged..