Yes, the terms Megabyte (MB) and Megabit (Mb) are confusing!
Please stop scratching your head and read the next two lines to make things clearer. Megabyte (MB) is used in the sense of file size. Megabit is used to express download speeds. The storage capacity of a CD is expressed in Megabytes (MB). Whereas internet speed is expressed as Megabits per second (Mbps). Now the question arises how are these two quantities related? The relation between the two can be easily expressed in an equation 1 bit = 1/8 bytes. Some people confuse with the two quantities and think that 1 Mega bit per second will allow them to download 1 Megabyte in one second. But now we have our equation right and we can clearly observe that to download 1 MB of file in one second you need an internet connection of 8Mbps.
Firstly, maximum bandwidth of a internet connection only allows for a relative comparison between two internet connections. We know from practical experience that it is almost impossible to get the actual internet speed at the maximum bandwidth of a Internet connection. This is especially true for faster speed connections.
When we check the speed as via browser showing speed of download as in Firefox. We need to multiply that by 8 to get speed of the ISP. The reason is that computer’s operating system and all the apps on it (web browsers, download helpers, torrent clients etc.) all measure data in Megabytes (MB). 1 byte = 8 bits. So, to get the speed in Megabits per second, we will have to multiply the speed shown by your browser by 8.