Java APIs

Hi all

I am facing the problem related to calculation of upload/download speed, what I have written the code it is not giving the accurate upload/download speed which is verified by speadtest.net website. In this code, I have used tcp protocol for uploading and downloading. I am calculating the upload/download speed in following way

download speed = (total packet received)/(total time taken to receive all packet)
upload speed = (total packet sent)/(total time taken to send all packet).

Please help me why I am not getting the accurate internet up/down speed result.