Travel · Japan · Type A/B · 100V
Japan: the plug fits, the voltage drops.
Japan is the one long-haul destination where your US charger slides straight into the wall: sockets are Type A, the same two flat parallel pins you have at home. The story is the voltage — Japan runs 100V, the lowest mains voltage on earth, on a grid split between 50Hz and 60Hz.
Japan vs the US wall, line by line
Japanese sockets are Type A (two flat parallel slots), with Type B — the same plus a round earth hole — in newer construction. A US two-prong plug is mechanically identical.
| Spec | Japan | United States | What it means for you |
|---|---|---|---|
| Plug type | A, plus B where a ground is fitted | A and B | Same shape — no plug adapter needed |
| Voltage | 100V | 120V | 17% lower; irrelevant to any 100–240V charger |
| Frequency | 50Hz east, 60Hz west | 60Hz nationwide | Only affects AC motors and mains-timed clocks |
Why 100V is harmless to your charger
Turn any USB-C brick over: the input line reads 100–240V ~ 50/60Hz. Japan's 100V is the bottom of that range by design. A switching supply rectifies mains to DC, then regulates — at 100V it draws slightly more current to deliver the same watts. A 30W charger stays a 30W charger.
What 100V does change is anything that turns volts into heat. Power in a resistive element scales with the square of voltage, so a US 120V hair dryer on 100V makes roughly 69% of its rated heat — safe, just slow. Japan is the only country where a US 120V-only device is undervolted rather than destroyed; compare the Philippines, where an identical-looking socket carries 220V.
The 50Hz / 60Hz split
Eastern Japan — Tokyo, Yokohama, Sendai, Sapporo — runs 50Hz. Western Japan — Nagoya, Kyoto, Osaka, Hiroshima, Fukuoka — runs 60Hz, a legacy of Tokyo buying German generators in the 1890s and Osaka buying American ones. It matters for two things: synchronous AC motors (a turntable, an old clock radio) and anything that counts mains cycles for time. Every switching supply you own is rated 50/60Hz.
What to pack
- Ground
3-prong to 2-prong grounding adapter
Fixes the only physical incompatibility in Japan: a grounded US plug facing a two-slot outlet.
- Converts
- NEMA 5-15P to 1-15R
- Weight
- Under 30g
- Use
- Laptop cords, CPAP
- 30W
Anker 511 Nano 3 30W
A folding single-port GaN brick that plugs into a Japanese socket unmodified.
- Output
- 30W USB-C PD
- Input
- 100–240V
- Prongs
- Folding, Type A
- 65W
UGREEN Nexode 65W GaN 3-port
One brick for laptop, phone and earbuds — one hotel outlet is enough.
- Output
- 65W shared
- Ports
- 2× C, 1× A
- Input
- 100–240V
Works as-is vs genuinely needs a converter
Everything with a 100–240V input works: phones, tablets, laptops, cameras, e-readers, toothbrushes, shavers and every US USB charger of the last decade.
A voltage converter is a different device — a transformer that changes the voltage itself — and Japan travelers almost never need one, because 100V is below 120V rather than above it. The exception is anything that must hit a set temperature: a curling iron on 100V may never get there, and a travel kettle takes longer. Buy dual-voltage versions instead. See adapters vs voltage converters and travel adapter vs converter.
Elsewhere in the region
FAQ
Do I need a plug adapter for Japan?
No. Japanese sockets are Type A, the same two flat parallel pins used in the US, so a two-prong plug fits directly. Pack a three-prong to two-prong grounding adapter for older buildings with no earth hole.
Will my charger work on Japan's 100V?
Yes. Every USB charger sold in the US is rated 100 to 240 volts and Japan's 100V is the bottom of that range; it draws slightly more current and delivers the same wattage.
Does the 50Hz and 60Hz split affect my devices?
No. Every phone, laptop, tablet and camera charger is a switching supply rated 50/60Hz. Frequency only matters to synchronous AC motors and mains-timed clocks.
Will my US hair dryer work in Japan?
It runs, weakly. Heat falls with the square of voltage, so a 120V dryer on 100V makes about 69% of its rated heat — safe but slow. A dual-voltage travel dryer is the better answer.