The voltage in Greece is 230V, 50Hz frequency. For Americans with 120V (single voltage) devices, you'll need a voltage converter (expensive and heavy). However, for dual voltage devices that can run on either 110V or 220V (the vast majority of cell phones, tablets, laptops, etc), all you'll need is an adapter plug like this one that I carry. Note: Most hairdryers and styling devices are single voltage. Every hotel will have a hairdryer, leave that at home. If there's a styling tool you can't live without, invest in one that's dual voltage before you go.