Transformers & Voltage Converters

So you've found yourself a suitable travel adapter that will allow you to plug all of your devices into the outlets in the country that you are about to visit - job done right? Unfortunately life's not quite that simple. Travel adapters will allow you to physically plug your devices into an outlet that it was not designed to fit. Useful, but that's all it does - travel adapters do not change the voltage or frequency of the mains supply, at least the vast majority don't.

In the US the mains supply is specified as 120 V + /- 5% and your electrical devices will probably function quite happily on a voltage anywhere in the range 114 - 126V. If you are travelling abroad and the local mains supply is in the range 220 - 250V then you will need to check if the devices that you want to take with you are compatible or not. Take a laptop as an example, they are designed for portability and will often be marked (maybe on the power supply) 100 - 240V 50/60Hz. The same is often true of phone chargers, shavers and the like. If the devices that you want to take are not specifically marked like this then you can be pretty sure that they are not compatible and you will need to do something about it.

If you plug a European hairdryer (designed to work on 230V) into a lower voltage US outlet (120V) it is unlikely to work well, if at all, and you may damage it as well. If you plug an American hairdryer (designed to work on 120V) into a higher voltage European outlet (230V) you can expect fireworks - very dangerous and not recommended.

If you need to take devices to an area where the mains supply is 220 - 250V you will need to get a step down transformer / converter to power any devices that are not fully compatible. Although these two terms are often used interchangably there are some important differences that you need to understand in order to ensure that you end up taking the right kit.

To check local voltages around the world you can look at our voltage map of the world. Alternatively we have more detailed informaion if you search by country.

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Voltage Converters vs Transformers

These pieces of equipment "convert" voltage in different ways which in turn affects (amongst other things) what type of devices you can plug into them. Mains electricity is a sine wave - on a 120V supply the voltage will rise smoothly from 0 - 120V then drop to negative 120V before rising back to 0V. This is one cycle of the sine wave which happens 60 times per second so the supply frequency is 60Hz.

In order for a transformer to change a 230V supply into 120V it reduces the amplitude of the sine wave by roughly half but it still remains a true sine wave. A voltage converter on the other hand effectively "chops" the peaks of the sine wave off. That results in a chopped wave that approximates 120V.

Electronic devices that have circuits and chips such as TVs, computers, chargers etc. require a power supply that is a true sine wave so you have to use a transformer to power them. Simple electric devices such as heaters and simple motors are more tolerant and can be run on the chopped waveform so you can use either a converter or a transformer.

Voltage Converters

American travelers may find a voltage converter from 220V to 110V will be useful as the majority of countries outside of Central & North America use 220V - 240V. Popular holiday destinations like the UK, France, Italy and Spain will likely require a voltage converter for Europe.

Features:

• Usually cheaper
• Usually lighter as they are solid state (a 500w converter should weigh less than 0.5kg / 1lb)
• Can only power simple electric devices not electronics
• Cannot be used continuously for extended periods of time (more than about 3 hours)

You can pick up low powered (100W) converters very cheaply and they often take up no more space than a plug adapter. When choosing a voltage converter however it is generally recommended to get one that is rated at 2 - 3 times the wattage of the appliance that you want to plug into it. That means that if you have a device that says it is 35w you should get a 100w converter to have a safe margin.

Transformers

American travelers may find a step down transformer from 220V to 110V could be useful if electronic devices (not just for charging phones / tablets etc) or medical quipment need to be powered outside of Central & North America as the majority of countries use 220V - 240V.

Features:

• Can power both electric and electronic devices
• Can be used continuously for extended periods
• The power supply of choice for critical equipment eg medical devices
• More expensive than converters
• Bulky and heavy (a 1000w transformer can weigh 7 - 10kg / 15 - 20lbs)

When choosing a transformer it is necessary to get one that is rated at a wattage that is a minimum of 25% higher than the device that you are going to plug into it. Transformers should run happily for extended periods of time (overnight) at 80% of their rated capacity.

Many devices draw more power on start up than in normal use and you have to accomodate this so always build in as much margin as is practical and you can afford. For this reason it is generally recommended to get one that is rated at 150% or more the wattage of the appliance that you want to plug into it.

High powered transformers are generally not practical for travelers due to their size and weight. They may be the only option however if you have critical pieces of equipment that you absolutely have to take with you such as medical devices.

Frequency

AC frequency refers to the number of cycles or times that the current reverses direction in a second. In the USA & Canada the supply frequency is 60 Hz whilst in the UK, Europe and most of the rest of the world it is 50 Hz. Voltage converters and transformers will only change the voltage, not the frequency. There is no practical way of altering the frequency of a supply.

If the country that you are going to operates at 50Hz it makes little practical difference as most travel appliances will run at either frequency. Some items with motors, such as hairdryers and some clocks will run at a slightly different speed than intended but it is not likely to be particularly problematic.

Check your device - it may say 50/60 Hz which indicates that it is compatible with either frequency. If you are in doubt or have critical or expensive equipment check with the manufacturer first as some equipment may be damaged by running on an incorrect frequency.

Practical Information

European Shaver Sockets

Surge Protectors / UPS

Surge protectors and UPS (Uninterruptible Power Supply) deisgned for use in the US should not be used in countries with 220 - 250V mains supply. The network is set up differently and you may damage your equipment even when using a voltage converter or transformer.

This means that domestic power strips with integral surge protection should not be used with an incompatible mains supply. Instead you should purchase a suitable surge protected adapter designed for the job if required. Where these are available we have specific recommendations if you search by country.

Japan

Japan operates on 100V which is technically not compatible with US appliances as it is too low (US voltage is currently specified as 120 V + /- 5%). The difference is however small and many appliances will still work perfectly well.

If you have sensitive or expensive items such as medical equipment or computers you should check to see if they will work. Items such as these will often specify "100 - 240V" either on the equipment or the power supply (if it has one). If not then you may need a special transformer to run your equipment even though a plug adapter may not be necessary.

If you need a specialist 100V transformer try these:

• 100V Step Up / Down Transformer (200W) (Suitable for US devices being used in Japan or Japanese devices being used in the US).
• 100V Step Down Transformer (1600W) (for using Japanese devices in the US - will not allow you to use US devices in Japan).

Frequently Asked Questions
About Voltage Converters / Transformers

What is a voltage converter?

A voltage or power converter is a compact and economical device that converts the electrical output of a outlet by either increasing or decreasing its voltage. This is useful for American travelers as it can provide a 120V supply from a 230V outlet. Due to the way in which they work (essentially providing a chopped DC output) they are suited to simple electric devices and are not generally suitable for powering most electronic items such as desktop computers.

What is a step down transformer?

A step down transformer converts a 230V outlet to a 120V supply that can be used to power American devices. As they provide true AC output they can be used to power electronic items as well as basic electric ones. They are heavy, bulky and expensive in comparison to voltage converters however so are generally not appropriate for travelers unless critical equipment (such as medical) needs to be powered.

How do I use a voltage converter / transformer?

Just plug the voltage converter or transformer into a wall outlet and then plug your device into the converter / transformer. Transformers may have a selector switch or dedicated outlets for different voltage outputs.

Do I need a voltage converter for Europe?

American travelers to Europe may need a voltage converter or transformer as the local voltage (230 V 50 Hz) is outside the normal US range (120 V + /- 5%). Many US appliances however are dual voltage, in which case they will be marked "100 - 240V" or similar and will operate safely. Some high powered items (eg hair dryers) are single voltage however and would require a voltage converter or transformer to operate safely. Travelers will need to check their individual appliances in order to know if a voltage converter or transformer is required.

Do I need a voltage converter for {insert country}?

Use our search by country form on this page to check the local voltage in your destination and see if you need a voltage converter or transformer.

Do I need a voltage converter to charge my phone abroad?

No, you may need to select a plug adapter with onboard USB or USB-C and the appropriate charging cable. USB charging ports usually work with input voltages of 100V - 250V so a voltage converter is not normally required specifically for charging your phone. If you are using a dedicated phone charger (as opposed to USB) you will need to check for voltage compatibility.

Can you take a voltage converter on a plane?

Yes, voltage converters and transformers can safely be taken in carry-on or checked bags (due to their weight transformers may need to go in checked baggage). They do not contain batteries so present no danger.

General FAQs

Search Power Adapters
by Country

Which country are you visiting?

If you are visiting several countries, consider a universal travel adaptor for worldwide use.

Useful Information

♦ Global Voltage Map ♦ Global Plug Types Map ♦ Plugs & Sockets of the World ♦ Interactive map of the World ♦ 10 Must have travel accessories ♦ What about my hair straighteners?