Last updated: 4 January 2025
When you are going on a trip to Japan, be sure to pack the appropriate travel plug adapter that fits the local sockets. But what do those electrical outlets look like? Japan uses the U.S. standard: types A & B.
The standard voltage in Japan is 100 volts, which is a bit lower than the North American standard of 120 volts. This means that some American appliances may not work optimally in Japan without a voltage converter, but most modern electronics like laptops and phone chargers are dual voltage (100-240V) and will work just fine in Japan.
The frequency is 50 Hz in Eastern Japan (Tokyo, Yokohama, Tohoku, Kawasaki, Sapporo, Sendai and Hokkaido) and 60 Hz in Western Japan (Osaka, Kyoto, Nagoya, Shikoku, Kyushu and Hiroshima). This is a confusing and rather unique situation. Japan is the only advanced nation in the world with two separate power grids. Fortunately, frequency is unlikely to cause you any difficulty, because most electrical items are able to operate at different frequencies. Some items may be affected, such as clocks, but most appliances should be fine.
Unpolarised Japanese type A plug with prongs of equal width and without holes
There are two types of domestic wall outlets in use in Japan: the ungrounded type A (NEMA 1-15) and the grounded type B (NEMA 5-15).
The most common plug type in Japan is the ungrounded type A plug. It has two flat parallel prongs, which are 1.5 mm thick, measuring 15.9 – 18.3 mm in length and spaced 12.7 mm apart. In the U.S., type A plugs are generally polarised and can only be inserted one way because the two blades do not have the same width. In Japan, type A plugs are often unpolarised and can mostly be inserted either way.
Japanese type A plug with separate ground wire
Japan also uses the grounded type B plugs: they are similar to type A, but they also have a 4.8 mm diameter round or U-shaped earth pin, which is 3.2 mm longer than the two flat blades, so the device is grounded before the power is connected. However, type B is much less common than type A. In older homes, the only places with grounded outlets are wet areas such as the kitchen, bathroom, laundry room, etc.
Since 2005, new Japanese homes are required to have grounded sockets for connecting domestic appliances. But instead of type B plugs, Japanese appliances often come with a type A plug and a separate green/yellow cable, which is the protective earth. This ground wire has to be screwed onto the socket.
The video below shows how you connect a grounded appliance to a Japanese outlet.
Type A and B plugs are not insulated (i.e. the pin shanks are not sleeved; they do not have a black covering towards the plug body like type C, G, I, L or N plugs) and the outlets are not recessed into the wall, which means that if a the plug is pulled halfway out, its prongs are still connected to the socket. Type A and B sockets are notoriously dangerous, since the distance between the receptacle and a partially pulled-out plug is big enough to touch the pins with your fingers or with a metal object such as a teaspoon.
Click here for a global map showing the spread of the different plug types used around the world.
Click here for a detailed list of the countries of the world with their respective plug and outlet types, voltage and frequency.
