What are Vietnam's power outlets and voltage? Adapter plugs and whether you need a transformer

ベトナムの電源は220Vが基本です。コンセントの形より先に、充電器や家電の「INPUT」を見てください。「100–240V」とあれば多くの場合は変圧器不要ですが、「100V」のみなら、そのまま挿すと故障や発熱の危険があります。

スマホ充電器は海外対応でも、ドライヤーや美容家電は100V専用が残っています。また、モバイルバッテリーの個数・容量・機内での使用ルールは航空会社ごとに違います。この記事では、電圧・プラグ・航空ルールを分けて確認します。

先に結論：持参前の確認順

• 機器本体または充電器のINPUTが100–240Vか確認
• 100V専用の高出力家電は、旅行用の海外対応品へ替えることも検討
• A/C対応の小型変換プラグを一つ用意
• モバイルバッテリーはWh表示と搭乗航空会社の個数制限を確認し、手荷物へ

Vietnam's voltage and plugs

How to tell the plug shape

The outlets you'll see in Vietnam are mainly two kinds. Knowing the shapes saves you from panicking "it won't fit" on the ground.

• Type A— The same two flat prongs as Japan. At newer hotels' A/C dual-compatible outlets, it often plugs in as is
• Type C— Two round prongs. Common in Europe and the standard in Vietnam. In rural areas and older buildings it may be C-only
• Rarely, Type D or F— Very occasionally seen in old buildings and the like. Have a multi-type plug adapter and you'll almost never have trouble with the shape

Can Japanese appliances be used as is?

Since Japanese plugs are Type A, they often plug into A/C dual-compatible outlets as is. The issue, however, is voltage. Plugging a Japanese 100V-only product in as is risks failure, so checking the compatible voltage is essential.

• Products compatible with "100–240V"— Many chargers for phones and laptops fall here, and no converter is needed
• 100V-only products— Some hair dryers and beauty appliances. A voltage converter is needed to use them
• If the plug won't fit— For C-only outlets in old rural buildings, an A/C adapter gives peace of mind

A quick-reference chart by device

Things to have for peace of mind

• An A/C-compatible plug adapter (a multi-type is handy)
• A charger labeled "100–240V" compatible
• A charger or mobile battery with many USB ports (to charge several devices at once)

How to choose a plug adapter and charger

• A multi-type plug adapter— If it covers A/C plus countries worldwide, you can reuse it on other trips
• Consolidate into a charger with USB ports— Charge a phone, earbuds, and camera at once from one unit, saving outlet slots
• USB-C PD compatible— If you can cover a laptop or tablet with a single charger too, luggage shrinks
• A GaN (gallium nitride) charger is handy— Small and light at the same output, and a model with several USB-C ports lets you consolidate into one charger. Fewer outlet slots and less luggage
• A small power strip— Hotels may have few outlets, and being able to multiply one slot is convenient

The hotel power situation

A common gripe at hotels is "there's no outlet where I want to charge." Knowing in advance makes it easier to cope.

• Few outlets— Older hotels may have only a few in the room. A charger with many USB ports or a small strip lets you charge several devices at once
• None by the bedside— You may want to charge at your pillow but there's no slot nearby. Having one longish charging cable gives peace of mind
• Power cuts off when the card key is removed— Some hotels cut room power when you pull the key from the in-room card-key holder. To charge while out, find another always-on outlet or ask the front desk

How to choose when you need a voltage converter

A voltage converter (transformer) is needed only when using devices not compatible with "100–240V." When choosing, always check that it handles the device's power consumption (W).

• Check the power consumption (W)— Choose a converter with a rated capacity larger than the wattage shown on the device. High-output devices like hair dryers need a converter with a larger capacity too
• The option of going overseas-compatible in the first place— Using a travel "100–240V" hair dryer or hair iron means no converter is needed and lighter luggage
• A plug adapter and a voltage converter are different things— A plug adapter only matches the "shape" and doesn't change voltage. When you want to lower the voltage, a converter is needed

Handling mobile batteries

モバイルバッテリーやリチウム電池は、飛行機では預け入れができず機内持ち込みが原則です。容量はWh（ワットアワー）で見るのが基本で、おおまかに10,000mAhで約37Wh、27,000mAh前後で約100Whが目安です。100Wh以下でも個数制限は航空会社ごとに異なります。たとえばVietjetは100Wh以下を最大2個と案内しています。100〜160Whは事前承認の対象になることがあり、160Wh超は通常持ち込めません。必ず利用会社の規定を確認してください。

Vietnamese airlines restrict in-flight use of mobile batteries

Vietnam Airlines and VietJet Air restrict in-flight use of mobile batteries for safety. Not being able to check them is common to all carriers, but Vietnamese airlines require extra care with in-flight handling.

• Charging in flight is not allowed— Using a mobile battery to charge a device during flight is prohibited. Turn it off and store it
• Don't put it in the overhead bin— You're asked not to put it in the overhead bin but to keep it in a visible place around your seat
• Charging via the in-seat USB port is also not allowed— Using the seat's USB port to charge the mobile battery body itself is also prohibited
• Check the latest rules with each carrier— Since capacity and quantity limits and operations can change, check the official guidance of the airline you're flying before departure

Points to note

• Always check the compatible voltage on the "INPUT" label of chargers and adapters
• Don't use 100V-only high-output devices (hair dryers, etc.) without a voltage converter
• At some hotels you can borrow a plug adapter at the front desk

Frequently asked questions

What are Vietnam's voltage and plugs?

The voltage is 220V and the frequency is 50Hz. Plugs are mainly A and C types, and A/C dual-compatible outlets are common too. Since Japan is 100V, you need to check your devices' compatible voltage.

Can I use my Japanese phone charger as is?

Many phone and PC chargers are "100–240V" compatible, so they work without a converter. The Japanese Type A plug often plugs in as is too, but having a plug adapter gives peace of mind for C-only outlets.

Do I need a voltage converter?

Not for a "100–240V" compatible device. A converter is only needed when using a Japanese 100V-only product (some hair dryers and beauty appliances, etc.).

Are there enough outlets at hotels?

Mid-range and up hotels have several in the room, and USB-port ones are increasing. However, some rooms have few, or no slot by the bedside, so a charger with USB ports, a small power strip, and a longish charging cable let you charge several devices at once, which is handy.

Can I bring a mobile battery on the plane?

機内持ち込みが原則で、預け入れはできません。容量はWhで見て、100Wh以下でも個数制限は航空会社ごとに異なります（10,000mAhで約37Whが目安）。Vietjetは最大2個と案内しています。機内での使用や座席USBでの充電にも制限があるため、搭乗する航空会社の最新の案内を確認してください。

Please also check the overall packing list and the season together.

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まとめ：変換プラグより先にINPUTとWhを見る

スマホやPCは100–240V対応が多い一方、100V専用家電は別です。ラベルを読まずに判断しないことが最重要です。モバイルバッテリーは預けず、端子を保護して機内手荷物へ入れ、個数・使用・保管場所は搭乗航空会社の最新規定に従ってください。