Copied from an old "The Screen Savers News Leter:
Q: What is the difference between MB and Mb? Is there a conversion factor?
-- A freakishly loyal viewer
A: The big "B" in MB stands for byte. The lowercase "b" in Mb stands for bit.
In terms of data storage values, there are eight bits in every byte. A megabit is composed of 1,048,576 bits, whereas a megabyte represents 8,388,608 bits: eight times as many.
But wait a minute -- doesn't the capital M in MB or Mb stand for mega, and doesn't mega imply one million? If this is true, then how could a megabit be 1,048,576 bits? That's 48,576 too many bits!
Let's use kilobits to explain the reasoning. Computers thrive on binary language: ones and zeros. A binary kilobit, and we use binary values to represent storage capacities, is actually 1024 bits (2 to the 10th power). Back in the day, sloppy computer engineers noticed that 1024 was awfully close to 1000, so they just hijacked the decimal prefixes most people are familiar with and used them to describe storage capacities.
Problem is, hard drive makers tend to use the decimal scheme rather than the binary scheme they should be using. This is partially why when you install a 30GB hard drive Windows tells you the drive is only about 28GB. Formatting the drive also consumes some space.Because this is all somewhat confusing, The Screen Savers has created a conversion chart for you to print out, trim around the edges, and carry in your wallet. You might find it useful the next time you visit the computer store.
photo of chart omitted