Adapter or converter?
An adapter changes the shape of the plug. A converter changes the voltage behind it. They are not alternatives to each other, and almost everything in a modern bag needs only the first.
What an adapter does, and the three things it cannot do
A plug adapter is a passive lump of plastic and brass. It carries the live and neutral connections through to a different pin arrangement, and that is the whole of its function. It cannot change the voltage arriving at your device, it cannot change the frequency, and it cannot invent an earth connection that your plug does not have.
That last one is the trap, because an adapter can quietly lose an earth connection that you did have. A two-pin Europlug slides into an earthed German socket perfectly and carries no earth at all. We have 13 of those pairings on file; they are set out in what earthing protects against.
Two very different things are sold as "converters"
This is the distinction that decides whether the thing you bought will work, and it is usually left out.
A transformer
Wire wound on an iron core. It steps the voltage up or down and hands the device a clean sine wave, which means it is safe for anything: motors, circuit boards, heating elements. It is rated for continuous use. It is also heavy — enough capacity for a hair dryer means several kilograms of iron, which is why you rarely see one in a travel shop.
A "travel converter"
Light, cheap, and a different device entirely. Most are solid-state units that chop the mains waveform rather than transforming it, discarding part of each cycle to reduce the average power delivered. What comes out is not a sine wave. That is acceptable to a heating element, which does not care about waveform, and damaging to anything with a motor or a power supply in it.
They are also duty-cycle limited. A unit sold as "2000 W" will often say, further down the box, that it is good for fifteen minutes at a time. That is not a safety margin being conservative; it is the rating.
So the rule is: a travel converter may feed a resistive load, briefly. It must never feed a laptop, a camera charger, a shaver, a CPAP or anything with a motor. And if the device you wanted it for was electronic, you did not need one anyway — see below.
Most of your bag needs neither
Of the 28 device classes this site tracks, 15 are dual-voltage: their power supply accepts anything from about 100 V to 240 V and regulates internally. Phone and laptop chargers, camera batteries, power banks, e-readers. For all of these the answer is a plug adapter and nothing else, anywhere in the world.
The remaining 13 are built for one voltage. Of those, 9 are heating elements, and those are the ones where a converter is the wrong answer rather than an expensive one:
| Device | Typical draw | Honest advice |
|---|---|---|
| Full-size steam iron | 1000–2400 W | Buy a dual-voltage one, or use the hotel’s |
| Hair dryer | 1200–2000 W | Buy a dual-voltage one, or use the hotel’s |
| Handheld clothes steamer | 800–1600 W | Buy a dual-voltage one, or use the hotel’s |
| Travel kettle | 600–1000 W | Buy a dual-voltage one, or use the hotel’s |
| Travel iron | 400–1000 W | Buy a dual-voltage one, or use the hotel’s |
| Baby bottle warmer | 100–500 W | Dual-voltage versions are common and cheap |
| Hair straightener | 30–250 W | Dual-voltage versions are common and cheap |
| Curling iron or tong | 25–200 W | Dual-voltage versions are common and cheap |
| Electric blanket | 60–200 W | Dual-voltage versions are common and cheap |
A dryer pulling 1800 W is asking for more continuous power than any travel converter will deliver, and the failure is not subtle. The reasoning is in why hair dryers fail abroad.
Neither one touches frequency
No adapter and no converter changes 50 Hz into 60 Hz. In practice this matters for very little: of our 28 classes, only 2 are frequency-sensitive — things with a synchronous motor or a mains-derived clock, which will run slow or fast rather than break. Everything with a modern power supply is indifferent to it.
The short version
- Reads 100–240 V? Plug adapter. Done.
- Single voltage, and it heats? Leave it. Buy one there or use what the accommodation provides.
- Single voltage, and it does not heat? A transformer will run it. A travel converter will not, whatever the box says.
- Metal case? Check the adapter carries the earth through.
Not sure which of those you are holding? The marking on the plug says so directly — or run your trip through the tool and it will tell you for everything at once.