Same as for the rest of the EU, the power supply in the Netherlands is 230V, or 50-60 hertz. If you visit the Netherlands from another European country (France, Spain, Germany...), you can plug in your device without any issues. Travelers from the UK need a simple travel plug adapter, as the sockets in continental Europe are different from the ones in the UK, while the voltage is the same. Travelers from the US (and other low-voltage countries) need a step down voltage converter to use their devices in the Netherlands.