Data transfer rates

[brian873]

Hi I would like to know the calculation so I can work out data transfer rates on my lan.

I have found online calculators that do the job but I would like to know how they do it!

Any advice is welcome.

Thanks

brian

An example would be:

"It takes 1 minute to download a 7.5 MB data file. At what bit rate is the data being transferred?"

[RJM]

7.5MB / 60seconds = 125KB per second

125KB per second * 16 ( bits per word ) = 2Mb per second

Edited November 19, 2007 by RJM

[brian873]

Hi RJM, thanks for the reply. I seem to have come with a different figure form you.

Can anyone confirm what it right?

Thanks

7.5Mb = 7,500Kb = 7,500,000 bytes = (7,500,000 x 8 bits = 60 million bits. Divide that by sixty seconds in a minute and you get a data rate of 1 million bits per second or 1Mbps.

[ripken204]

Hi RJM, thanks for the reply. I seem to have come with a different figure form you.

Can anyone confirm what it right?

Thanks

7.5Mb = 7,500Kb = 7,500,000 bytes = (7,500,000 x 8 bits = 60 million bits. Divide that by sixty seconds in a minute and you get a data rate of 1 million bits per second or 1Mbps.

i'm pretty sure you are right. for some reason RJM multiplied by 16 which should have been 8, at least as far as i know it should have been 8

[Tarun]

Actually, 7.5MB = 7,864,320 bytes.

Try out Converber, it may help you a lot brian.

[brian873]

Hi guys thanks for this.

TARUM: I still get 7,500,000 bytes when using that utility. Thanks for that by-the-way. Can you show me how your doing the calculation?

Thanks

[RJM]

Yup, I messed up. There are 16 bits per word ( which I mentioned ) but only 8 bits per byte. I should have multiplied by 8 bits per byte instead of

16 bits per word.

The correct rate is 1Mb/sec

Edited November 20, 2007 by RJM

[phkninja]

Brian- Ok here is how you calculate that

1024 bytes = 1KB

1024 KB = 1 MB

1024 MB = 1GB

etc

the reason for 1024 is to do with information being stored in binary (in bits). 1024 is 2^10.

Therefore 7.5MB = 7.5 * 1024 *1024 = 7864320 bytes

This makes your calculation into

7864320 / 60 = 131072 bytes per second, * 8 bits = 1048576 bits per sec, = 1024 Kb/s or 1Mb/s

Just so you know some manufacturers of hard drives have been fined in Europe for advertising a hard drives as having more space because they use the wrong conversion e.g. 500GB, they use 1000 bytes = 1Kb etc, so they are actually selling 465GB of space ((500*1000*1000*1000 )/ (1024*1024*1024))

This is also why in Windows when you look at a hard drives space info it will say one figure for bytes and something different for GB, e.g. 4,550,839,296 bytes used (4.23GB used)

Edited November 20, 2007 by phkninja

[brian873]

Thanks guys !

I think I have found out what I need....

Thanks again for taking to the time to answer.