4.7 - Misconceptions on Units

There is always a misconception in unit conversion on Mbps, MB/sec, Kbps, KB/sec, MB, KB, Mb, Kb. In speed calculation 1 Mbps = 1000 Kbps (not 1024 Kbps), it is a common misconception to use 1024 in conversion between kbps and bps. However, if you are calculating storage it is correct to use 1 MB = 1024 KB.

Example 1 (Speed):

If we are calculating speed, KB/sec and MB/sec: (round 2 digits)

408 KB/sec / 1024 = 0.398 MB/sec = 0.40 MB/sec (WRONG!)

408 KB/sec / 1000 = 0.408 MB/sec = 0.41 MB/sec (CORRECT!)

Please read the definition here:

http://compnetworking.about.com/library/glossary/bldef-kbps.htm

Example 2 (Storage):

If you are calculating storage such as harddrive space MB and KB: (round 2 digits)

408 KB / 1024 = 0.398 MB = 0.40 MB (CORRECT!)

408 KB / 1000 = 0.408 MB = 0.41 MB (WRONG!)

Please read the definition here:

http://compnetworking.about.com/library/glossary/bldef-kbyte.htm