US to Japan Plug Adapter & Voltage Guide (United States to Japan)

Using US Electronics in Japan

Most two-prong US (Type A) plugs physically fit into Japanese wall outlets without an adapter. However, three-prong US plugs (Type B) will NOT fit into most Japanese hotel sockets without a 3-to-2 prong grounding adapter, as Japanese residential outlets rarely have an earth hole.

Direct Verdict for Travelers

Electrical Specification	United States (Source)	Japan (Destination)	Traveler Impact
Nominal Grid Voltage	120 Volts	100 Volts	Voltage Compatible
Grid Frequency	60 Hz	50 Hz	AC motors run at altered speed; digital chargers unaffected.
Standard Plug Types	Type A, B	Type A, B	Physical fit possible for some outlets.

Visual Pin & Socket Comparison

United States Plugs

Type A

Type B

Japan Wall Outlets

Type A

Type B

Key Electrical Gotchas in Japan

Japan runs on 100V, the lowest residential voltage in the world. While US 120V electronics will not burn out, heating appliances (hair dryers, kettles) may take 20-30% longer to heat up.
American polarized plugs (where one blade is slightly wider than the other) might struggle with older Japanese non-polarized outlets where both slots are the same narrow size.
Japan is divided into two distinct electrical frequencies: Eastern Japan (Tokyo, Yokohama) runs at 50Hz, while Western Japan (Kyoto, Osaka, Hiroshima) runs at 60Hz. Modern digital electronics handle both without issue, but older motorized clocks or vintage audio gear will run at incorrect speeds.

Device Category Breakdown

Smartphones, Tablets & Laptops

Works immediately with 2-prong chargers. If your laptop cord has a 3rd round grounding pin, you will need a 3-prong to 2-prong adapter.

Hair Dryers, Straighteners & Heated Tools

Will run slightly weaker due to the 100V supply compared to 120V, but will not suffer catastrophic over-voltage damage.

Shavers & Personal Grooming

Fully functional.

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