In this guide
A travel adapter changes the plug shape so it fits a foreign outlet — it does nothing to the voltage. A voltage converter actually changes the voltage to match what your device needs. Most modern electronics are dual-voltage and only need an adapter; older or high-wattage appliances may need a converter.
- Your device says 100–240V on the label — use a travel adapter only
- Your device is single-voltage and you pair it with the correct step-up or step-down converter
- You verify the wattage rating of the converter matches or exceeds your device
- You use only a travel adapter with a 120V-only device in a 240V country — it will fry the device
- You use the converter in the wrong direction (step-up when you need step-down)
- Your converter’s wattage rating is lower than your device’s draw
What a Travel Adapter Does
A travel adapter is purely mechanical. It reshapes the plug so it physically fits into a foreign wall socket. It passes through whatever voltage the outlet supplies — 120V, 230V, or anything else — unchanged. If the country you’re visiting runs on 230V and your device only handles 120V, the adapter alone gives you no protection.
Laptops, phone chargers, and most USB power bricks print “100–240V” on their label or power brick. These are dual-voltage and handle any outlet in the world. All they need is an adapter for the plug shape.
What a Voltage Converter Does
A voltage converter (sometimes called a transformer) electronically steps voltage up or down. A step-down converter takes 220–240V from a European outlet and drops it to 110–120V for a US device. A step-up converter does the reverse. You need to match the direction and ensure the converter’s wattage rating is at or above your device’s draw.
Converters are bulkier and heavier than adapters. For travel, it’s almost always better to replace a single-voltage appliance with a dual-voltage version rather than pack a converter. Rick Steves covers this trade-off well and recommends the same approach for most travelers.
Quick Comparison
| Setup | Works? | Need | Note |
|---|---|---|---|
| Dual-voltage device abroad | Yes | Adapter only | Check label for 100–240V |
| 120V-only device in 240V country | Yes | Step-down converter + adapter | Match wattage rating |
| 220V-only device in 120V country | Yes | Step-up converter + adapter | Less common scenario |
| 120V-only device + adapter only in 240V country | No | — | Device will likely be damaged |
How to Check Before You Travel
- Find the label on the device or its power brick
- Look for the input voltage range — “100–240V” means dual-voltage
- If it shows only one voltage (e.g., “120V”), you need a converter for incompatible countries
- Check the wattage (W) or amperage (A) to size the converter correctly
If you’re troubleshooting a USB-C device abroad, also check our guide on why USB-C to HDMI stops working — power delivery issues can look similar. And if you’re connecting to a display while traveling, see whether USB-C can connect to HDMI for your setup.
Bottom line: A travel adapter is a plug-shape converter only — buy one for your destination’s outlet type. A voltage converter changes the actual voltage and is only needed for single-voltage devices. Check your device label first; if it says 100–240V, you need nothing more than an adapter.