Technology behind speed test

Question

Hi,

I was wondering what is the technology behind Internet Speed test, which some websites use to check your speed e.g; http://www.speedtest.net/

The reason behind this question is, i wanted to write my own with one more feature and that is to keep checking speed after some interval so that i can have better idea of what i am getting for what i am paying for.

I am not sure if this question belongs to stackoverflow, so please forgive me if it is not.

Thanks.

Answer 1

Download a reasonably large amount of data from the server (N bytes). Record how long it takes. (M seconds) Download rate is N / M bytes per second.

Repeat for upload.

Answer 2

You download file of known size and time is measured. then speed is file size / time.