International Power Adapters: What You Need to Know

Does every country has a separate standard?

Plugs feeding in to plug adaptors and sockets, close up
Stephen Smith / Getty Images

If you're planning on traveling internationally, pack a power adapter that matches the plug standard for your destination. If you don't have the right adapter or need more than a plug adapter, you could accidentally fry your hair dryer.

The many different plugs and standards across the countries make it necessary to check labels to reduce the risk of accidentally buying the wrong adapter or forgetting an essential converter.

A few important variations in standards between countries (or sometimes even within a country) include differences in:

  • Current
  • Voltage
  • Frequency
  • Outlet and plug shape

Current

The two primary standards for current are Alternating Current and Direct Current. The U.S. standard was developed during the famous war between Tesla and Edison. Edison favored DC, and Tesla preferred AC. The big advantage to AC is that it is capable of traveling greater distances between power stations, and in the end, it was the standard that won out in the U.S. 

However, not all countries adopted AC. Neither did all your devices. Batteries and the internal workings of many electronics use DC power. In the case of laptops, the power brick converts AC power to DC. 

Voltage

Voltage is the force with which electricity travels. It's often described using a water pressure analogy. Although there are several standards, the most common voltage standards for travelers are 110/120V in the U.S. and 220/240V in most of Europe. If your electronics are only meant to handle 110V of force, having 220V shooting through them will damage them. 

Frequency

The frequency of AC power refers to how often the current alternates each second. In most cases, the standards are 60 Hertz in the U.S. and 50 Hertz everywhere that uses the metric system. In most cases, the rating doesn't make a difference in performance, but it can occasionally glitch devices that use timers. 

Outlet and Plug Shapes: A, B, C, and D

plug types

Although there are a lot of different plug shapes, most travel adapters settle for the four most common. The International Trade Administration breaks these into alphabetical shapes A, B, C, D, and so on. Check a guidebook for your destination whether you need something beyond the usual four for your travels.

Is a Power Plug Adapter Sufficient?

Look at the back of your device where you find the UL listing and other information. In the case of laptops, the information is on the power adapter.

The UL listing tells you the frequency, current, and voltage that your device can handle. If you're traveling to a country compatible with those standards, you only need to find the right plug shape. 

Devices usually come in three types: those that only comply with one standard, dual-mode devices that comply with two standards (switching between 110V and 220V), and those compatible with a wide range of standards. You may need to flip a switch or move a slider to convert devices with dual modes. 

Adapter or Converter

If you plan to travel with a single-voltage device to a country with a different voltage, you need a voltage converter. If you travel from someplace with lower voltage like the U.S. to a place with higher voltage like Germany, you need a step-up converter, and if you travel in the opposite direction, you need a step-down converter. This is the only time you should use a converter, and remember that you don't need to use them with your laptop. In fact, you might damage your laptop if you do.

In rare cases, you may also need an AC converter to convert DC power to AC or vice versa, but your laptop uses DC power already, so do not use a converter with it. Check with the company that made your laptop to see what you need. If necessary, you may also be able to buy a compatible power adapter in your destination country.

Hotel Services

Many international hotels offer built-in wiring for their guests that don't require any special adapters or converters to use. Ask before your trip to see what your destination offers. 

Tablets, Phones, and Other USB-Charging Devices

The good news about USB-charging devices is that you don't need a plug adapter. Using one would probably ruin your charger. You just need a compatible charger. USB is standardized. Your charger is doing all the work to convert the voltage to the USB charging standard to power your phone.

USB may be the best hope for standardizing power charging for the future. USB and wireless charging systems may be steps toward the next "electric plug" solution for international travel.

Although the USB standard has changed over time 1.1 to 2.0 to 3.0 to 3.1, it has done so in a thoughtful way that offers legacy compatibility. You can still plug your USB 2.0 powered device into a USB 3.0 port and charge it. You just don't see the bandwidth and speed advantages USB 3.0 offers when you do. It's also easier to replace and upgrade USB ports over time than it is to rewire homes for new electrical standards.