It seems there is a lots n lots of confusion regarding customs duty calculation. See I am an importer and although I do not have any readymade software but the one I have made in excell sheets for my own day to day purpose is that I am pasting below ... Also attaching a live copy of it for your use . There is a bit of internall calculation that you wont understd in one day still smart brains will be able to calculate easily. Here it is ...