Take a look at the labeling on your product. Many electrical devices can be used in both regions -- they will be labeled "110-240 volts." If they are labeled "110-115 volts," they need to be converted for use in Europe. One exception is razors, because many bathrooms in Europe have a razor socket that can be switched between 110 volts and 240 volts.
Purchase a step-up transformer to convert the 110-volt equipment to 220-240 volts. You can get them on the Internet or often in airports. Verify that the transformer can handle the wattage needed by the equipment. This is often printed on the equipment's label. Heat-generating or motorized products like hair dryers can be more than 1500 watts, while an electric toothbrush will be under 50 watts.
Buy the correct plug adapter for the country you are visiting. Even if the device is multivoltage and you have determined that you don't need a transformer, you will need an adapter to convert the U.S. prongs to the European receptacles. A United Kingdom plug receptacle is different to a U.S. receptacle. Many European countries use different prong patterns, so check the labeling on the outlet converter you are buying.
