US to Europe Voltage Checker
US outlets supply 120 V at 60 Hz, European outlets 230 V at 50 Hz. Enter what the label on your device says to see whether a plug adapter is enough.
Sources: UK supply regulations Updated
Result
Needs a step-down transformer
The supply (230 V) is higher than the 120 V the device accepts. Plugged in with only an adapter it is likely to be damaged. Use a step-down transformer, or a version of the device made for 230 V.
Frequency: the label says 60 Hz only and this supply is 50 Hz. A transformer does not change frequency. Devices with motors or mains-timed clocks may run at the wrong speed; ask the manufacturer.
How to read the label
Look for the word INPUT on the device, its charger or its power brick. It is followed by a voltage or a range and a frequency.
- INPUT: 100–240 V, 50/60 Hz. Works on both supplies. You need a plug adapter, nothing else. Many phone and laptop chargers are like this.
- INPUT: 120 V, 60 Hz. Made for North America. On 230 V it needs a step-down transformer.
- INPUT: 220–240 V, 50 Hz. Made for Europe. On 120 V it needs a step-up transformer.
- A switch marked 115/230. Set it to the local voltage before plugging in.
What the checker does
It compares the voltage of the supply with the range printed on your device. There are three possible answers.
- The voltage is fine: the supply voltage lies inside the printed range.
- Check with the manufacturer: the supply is outside the printed range but within 10% of it, for example a device marked 220 V on a 230 V supply. We do not give a verdict in that band, because only the manufacturer knows the tolerance of the device.
- Needs a transformer: the supply is more than 10% away from what the device accepts, as with 120 V and 230 V.
If you enter the power of the device, the result also states the minimum rating for a transformer. Heating appliances such as hair dryers and kettles draw a lot of power and need a correspondingly large transformer; buying a dual-voltage or local version is often the simpler answer.
The two supplies side by side
| Region | Nominal voltage | Frequency |
|---|---|---|
| United States | 120 V | 60 Hz |
| Europe, including the United Kingdom | 230 V | 50 Hz |
These are nominal values; the voltage at a socket varies around them. We confirmed the 230 V, 50 Hz figure in the UK supply regulations. The other figures are the standard nominal values and were not checked against the IEC standard itself. This page is a guide to reading a label, not electrical safety advice. If the label is missing or unclear, ask the manufacturer or an electrician.
Frequently asked questions
Can I plug a US device into a European socket?
Only if its label covers 230 V. Many chargers and power supplies say “INPUT: 100–240 V, 50/60 Hz” and work anywhere with a plug adapter. A device marked 120 V only will be damaged on 230 V unless you use a step-down transformer.
Is voltage in Europe 220 V, 230 V or 240 V?
The nominal figure is 230 V. You will also see 220 V and 240 V quoted, and devices marked 220–240 V are made for this supply. In the UK the declared voltage is 230 V with a permitted variation of 10% above and 6% below, so anywhere from about 216 V to 253 V.
Does a plug adapter change the voltage?
No. An adapter only changes the shape of the plug. To change the voltage you need a transformer.
Can I multiply US voltage by a factor to get European voltage?
No. They are not two units for the same thing but two different supply standards. 120 V and 230 V are simply what the two grids deliver. What matters is whether your device accepts the voltage of the country you are in.
Does the frequency matter?
For most electronics, no, if the label says 50/60 Hz. Devices whose speed is tied to the mains frequency, such as some motors and clocks, can run at the wrong speed on the other frequency. A transformer does not change frequency.
Sources
- The Electricity Safety, Quality and Continuity Regulations 2002 (UK), regulation 27 — declared supply of 230 V between phase and neutral at 50 Hz, with a permitted variation of +10% and −6% (checked October 12, 2026)
- IEC 60038, IEC standard voltages — the international standard for nominal supply voltages: 230 V at 50 Hz across Europe, 120 V at 60 Hz in the United States. We could not read the standard itself; these two nominal figures were not checked against it.