Does iPhone need an converter in belgium

Do you mean a voltage converter or a plug converter? And what country are you from? If you're from the USA and going to Belgium you'll need a plug converter. Looks like the USA uses Type A and B while Belgium uses type E and maybe Type C. You shouldn't need a voltage converter though. Every iPhone charger I've ever had has been 100-240 volts so it changes depending on where you are. You can check your wall adaptor just to be safe though.