Do you have an appliance with a different voltage than the one supplied in your home area?
Perhaps you moved to a new country and brought an appliance(s) with you. I’ve experienced this myself after moving from Europe which is 230 V (volts) to North America where the standard voltage is 120V.
For smaller appliances like an electric toothbrush or cellphone, you might just need a small adapter that plugs into your charger that will fit into your wall socket. Many these days are designed with adapters that work with a range of 100V – 240V electrical sockets.
But for larger appliances such as a higher end coffee maker, treadmill or stand mixer to name but three, you might need to purchase a step up transformer or step down transformer.
The question is how can you tell if you need one? And if so, which one.
Ok, that’s two questions and there are a few others to ask. We’ll answer them below.
Why would I need a transformer?
A transformer can be used when you have an appliance(s) whose voltage doesn’t match your local power source.
A transformer is a box that plugs into your wall socket that offers the ability to match the voltage of an appliance(s) with the local voltage. You might need to increase or decrease the voltage depending on the situation.
For example, Europe uses a voltage of 230V and North American countries use 120V.
You would either require a step up (increase) transformer or a step down (decrease) transformer depending on your appliance(s) and local voltage.
For smaller, relatively low wattage devices like electric toothbrushes, shavers, phones and even laptops, you might not need a transformer. Many of these devices are equipped to use chargers with a wattage range of (for example) 100 V – 240 V meaning you could use them in both the EU and North America with a small travel adapter.
You would use a transformer for larger, higher wattage appliances and devices such as a high end coffee maker, mixer, treadmill and things of that nature that have higher wattage than small appliances have.
Step up vs step down transformer explanation
Some people think that when you have an appliance from Europe (for example) and try to use it in the US that you need to lower the voltage for the appliance to work.
In actuality the opposite is true. You need to match the voltage with the appliance, not the electrical socket.
So you would need to step up the voltage from 120V to the 230V required by the European appliance.
Conversely, you would need to step down the voltage if you wanted to use an American appliance in Europe or any other place where the voltage is higher than what your appliance requires.
Alternatively, you can purchase a combination step up AND step down transformer, which we’ll discuss below.
Step up/down transformer combination unit
This step up/down transformer unit enables you to use a variety of appliances from (for example) North America and Europe. So you can plug this particular unit into a 110V wall socket and then use it to power up to 3 x 230V output devices or 3 x 110V output devices at a time.
If you look on the right hand side picture, you see the back side of the unit where you select the input which must match the power source. So if you’re in the US where 110V is the norm, you’d select 110V.
Then if you had a device with a 230V output, you’d plug it into the front of the unit. In this instance the device would step up the power so that it provides enough power for your 230V device.
If the situation was reversed and your input was 230V, you’d select that on the back and plug your 110V device into the front and use it in step down mode.
Why do smaller appliances not require a step up or down transformer?
You probably recognize the AC adapters shown above if you frequently travel to countries where the electrical plugs are different from the ones at home. A plus receptacle in the US is different from one in Germany which is also different from New Zealand which is different from India.
A small AC adapter set can be handy to power small devices that you travel with such as your cellphone, laptop, tablet and electric shaver for example.
The good news is while smaller appliances like this may require a plug adapter when you travel, they are designed to work with a range of voltages.
If you check your device or its power cable, you’ll probably sees something like “input 100V – 240V” imprinted on it.
This means that this device can be used in countries that have a voltage anywhere between 100V and 240V without need for a step up or step down transformer. Lower wattage devices like these can be designed to handle the discrepancy simply by using an AC adapter like the ones shown above.
The reason that the 100V – 240V range is slightly different to the common 120 V (North America) and 230V (Europe) is to account for wattage loss and to give a bit of overlap to be safe.
It’s larger wattage devices that require a suitable transformer that we’ll discuss below.
Examples of common home appliances and their wattage
Appliances are generally marketed and sold with their stated wattage clearly marked. The wattage shows you the amount of electrical power that a device requires measured in watts.
As you can see, there is a wide range of wattage depending on the appliance. Some appliances even have a wide range of wattages. You can find dryers or washing machines that have a lower or higher wattage than other similar models.
For many small devices that are relatively low wattage such as cellphones and PCs, you often just need an AC adapter when travelling to account for the different plug design and don’t require a transformer.
Here are some common home appliances along with typical wattages.
| Appliance | Wattage |
| Blender | 300W – 500W |
| Cellphone | 2W – 4W |
| Coffee maker | 800W |
| Desktop computer | 80W – 150W |
| Dishwasher | 1000W – 1500W |
| Fridge | 500W |
| Hair dryer | 350W – 1200W |
| Laptop | 20W – 50W |
| Microwave | 1000W – 1500W |
| Video game system | 160W – 200W |
| Washing machine | 350W – 700W |
As you can see, some devices use far more than the 230V-240V high end wattage that common adapters supply and would thus require a step up or step down transformer if you’re trying to use the device in a foreign country.
If you don’t use the proper transformer, you can easily burn out or otherwise destroy your appliance.
What is a step up transformer?
A step up transformer is used when the voltage in your appliance is higher than the voltage supplied from your electrical sockets.
So if you were using a 230V European appliance in North America you would use a step up transformer to bring the supplied electrical current to what the appliance requires which is 230V.
What is a step down transformer?
A step up transformer is used when the voltage in your appliance is lower than the voltage supplied from your electrical sockets.
So if you were using a 120V North American appliance in Europe, you would use a step down transformer to bring the supplied electrical current to what the appliance requires which is 120V.
How do I choose a step up transformer that is right for me?
Determine the wattage of the appliance(s) you need the transformer for. Look for one that has more wattage than you require. So if you have an appliance that requires 1400 watts, you could get a 2000 watt transformer.
Or you could 100% sure and get a 3000 watt transformer since there is a much higher wattage offered and no chance you will be underpowered.
Remember too that if you plan to use several devices at the same time, your must choose a transformer that can handle the load. If you choose a 2000W transformer and want to operate your 1450W coffee maker and 1000W stand mixer at the same time, it won’t work as the combined wattage requirement of these two appliances (1450W + 1000W = 2450W) is higher than the 2000W load limit of the transformer.
Also carefully read the specs of your chosen transformer before purchasing it: You can find (for example) a 3000W transformer that after 30 minutes of continuous use, will drop to a 1200W supply. While this would be doable for an espresso coffee maker that is only used for a few minutes at a time, it wouldn’t work for a device that runs continuously that needs a wattage higher than 1200W.
A rule of thumb you may see mentioned: Determine the total wattage you require and then find a transformer that is at least 25% higher. Some even suggest taking your wattage requirement and buying a transformer with a 2.5x or 3x capacity i.e. if your maximum wattage requirement is 500W, your transformer would be a 1250W – 1500W model.
If you’re looking for a transformer to use for several appliances at different times and not simultaneously, find the highest wattage appliance that you have and size the transformer for that one since it’s the one that requires the most wattage.