Illustration of a Japanese double wall socket. Original photo: Batholith / Wikimedia Commons, Public Domain; background extended and composition adjusted with AI.
Japan's usual household electricity supply is 100V, with Type A sockets for two flat pins. Before taking a Hong Kong appliance to Japan, check the Input voltage and frequency on the appliance or charger. If its input range covers Japan's 100V supply and the local frequency, use a suitable plug adaptor. An appliance marked only 220–240V cannot be used on Japan's 100V supply with a plug adaptor alone.
How do Hong Kong and Japanese plugs and electricity supplies differ?
ItemHong KongJapanCommon plugType G, three rectangular pinsType A, two parallel flat pinsHousehold voltage220V100VFrequency50HzEastern Japan: 50Hz; western Japan: 60Hz
Tokyo uses 50Hz and Osaka uses 60Hz. An appliance marked for both 50/60Hz already covers this frequency difference; check the voltage separately. See the Japan National Tourism Organization's electricity guide for Japan's supply and plug details.
Check Input: USB output is a different specification
A charger's small print usually separates Input from Output. Input describes the electricity it can receive from the wall; Output describes the power it supplies to a phone or other device.
For example, “Input 100–240V~ 50/60Hz” covers Japan's 100V supply and both frequencies.
“Output 5V” or “20W” answers a different question and does not establish compatibility with Japan's electricity supply. For a phone, camera or laptop, check the charger you will take. For a hair dryer, hair straightener or another appliance connected directly to AC power, check its own label or manufacturer's manual.
Two practical examples: a charger and a hair dryer
Apple Hong Kong 20W USB-C power adaptor
Apple's official support page says its USB power adaptors support AC supplies from 100V at 50Hz to 240V at 60Hz, covering Japan's 100V and 50/60Hz supply.
For the Hong Kong version of the 20W USB-C power adaptor, the issue is therefore the shape of the three-pin plug. Use a suitable Type A travel adaptor; a separate transformer is unnecessary. Its 20W USB output and the wall supply's 100V are different specifications.
Panasonic Hong Kong EH-NE66 hair dryer
The Panasonic Hong Kong EH-NE66 product page specifies AC 220–240V and 1,700–2,000W. Its input range does not include Japan's 100V, so a travel adaptor alone is insufficient.
If taking a hair dryer or straightener, choose a model whose manufacturer explicitly supports Japan's 100V and the destination's frequency. Alternatively, confirm whether your booked room includes a hair dryer and leave yours at home.
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What do plug adaptors, USB chargers and transformers do?
- Travel plug adaptor: changes the connection between plug shapes. It does not raise Japan's 100V to the 220V required by a Hong Kong appliance.
- USB charger: converts AC electricity to the USB output supported by its specifications. Check its Input to determine whether it accepts Japan's supply.
- Transformer: changes AC voltage. Supplying a Hong Kong 220V appliance from Japan's 100V source requires stepping the voltage up to the appliance's specified input. Ask the manufacturer to confirm the required specifications first.
For portable travel appliances, choosing a model explicitly compatible with Japan's supply makes preparation easier. Ask the manufacturer to confirm transformer arrangements for high-power appliances; a normal travel plug adaptor cannot perform that function.
A checklist before departure
- Find the correct label: check the charger for rechargeable devices and the appliance itself for directly powered equipment. Note the Input voltage and frequency.
- Check 100V compatibility: ensure 100V is within the input range and the destination's 50Hz or 60Hz is supported. Visiting both Tokyo and Osaka requires support for both frequencies.
- Check the pins: prepare a suitable Type A travel adaptor for a Hong Kong three-pin plug. Confirm that it accepts the plug and meets safety requirements.
- Reduce what you pack: confirm whether your accommodation provides a hair dryer. Replace incompatible appliances with compatible models.
Make sure adaptors connect securely. Do not force a plug into a socket or connect several adaptors in a chain.
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