The voltage and frequency of alternating current (AC) electricity used in homes varies from country to country throughout the world. Typically either 110-volt AC (110V) or 220-volt AC (220V) are used.
Note that 110 volts and 220 volts are averages, since the voltage does fluctuate during usage. Most countries use 50Hz (50 Hertz or 50 cycles per second) as the frequency of their AC. Only a handful use 60Hz.
Of the over 200 countries listed below, most use 220-240 VAC. Others use between 100-120VAC. Some countries, including the United States, use dual voltages. 43 countries use 60Hz, while the rest use 50Hz.
The voltage and frequency of AC electricity varies from country to country throughout the world. Most use 220V and 50Hz. About 20% of the countries use 110V and/or 60Hz to power their homes. 220V and 60Hz are the most efficient values, but only a few countries use that combination. The United States uses 120V and 60Hz AC electricity.