Two different problems get mixed up: whether your plug fits the socket, and whether your device can handle the voltage. A plug adapter solves the first. Only a voltage converter, or a device that already accepts the local voltage, solves the second.
Plug adapters: shape only
An adapter changes the pin shape and passes the local voltage straight through. It is small, cheap and all most travellers need, because the things people usually travel with (phone, tablet, camera and laptop chargers) are almost always rated 100–240 V.
- A universal adapter covers most socket types in one block, and many include USB ports.
- If a device has an earth pin (for example a three-prong laptop lead), choose an adapter that keeps the earth connection.
Voltage converters and transformers: change the voltage
Mains voltage falls into two broad groups. North America, Japan and some countries in Central and South America and the Caribbean use about 100–127 V. Most of the rest of the world uses 220–240 V. A device rated only for one group needs a converter when used in the other:
- Step-down converters take 220–240 V down to 110–120 V for North American single-voltage devices.
- Step-up converters take 100–120 V up to 220–240 V for single-voltage devices from 230 V countries.
- The converter’s wattage rating must exceed the device’s. Heating appliances such as hair dryers, straighteners and kettles often draw 1,000–2,000 W.
- Many lightweight travel converters are designed only for simple heating appliances used for short periods, not for electronics. Check the converter’s instructions before plugging in anything with a circuit board.
How to check a device in 10 seconds
| Label says | What you need |
|---|---|
| INPUT 100–240V ~ 50/60Hz | Only a plug adapter, if the socket shape differs |
| 110V / 220V switch | Set the switch for the local voltage, plus an adapter if needed |
| 120V only | Fine in 100–127 V countries; a step-down converter in 220–240 V countries |
| 220–240V only | Fine in 220–240 V countries; a step-up converter in 100–127 V countries |
Never guess with heating appliances. A 120 V-only hair dryer plugged into a 230 V socket through a plain adapter can burn out almost instantly and is a fire risk.
Quick answers
Does a plug adapter change voltage?
No. A plug adapter only changes the shape of the pins so your plug fits the socket. The voltage that reaches your device is the local mains voltage.
How do I know if my device is dual voltage?
Read the INPUT line on the label or charger. “100–240V” means it works on any mains supply worldwide. A single value such as “120V” or “230V” means it does not.
What happens if I plug a 120 V device into 230 V?
It can be destroyed within seconds and may overheat or catch fire. Use a step-down converter rated above the device’s wattage, or buy a dual-voltage version.
Can I use a hair dryer abroad?
Only if it is dual voltage (often with a switch) or matches the local voltage. Hair dryers draw a lot of power, so converters big enough to run them are heavy; a dual-voltage travel dryer is usually the easier option.
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