The blue and yellow boxes at the top are the SI standard units and they use base 10. The powers of ten appear in the rightmost column. Mega is 106, for example. These are standard SI prefixes for the familiar powers of ten that increment by three powers (i.e. standard SI prefix + either bit or byte). The orange and green units at the bottom use binary multiples. This is because computers use binary and some measures still use these powers of two. 210 (1024) approximates 103 (1000) and this is what the kibibyte is and is close in value to the kilobyte. These binary equivalents go up in multiples of 210 and they become increasingly distant from their SI equivalents as they get larger. This is because you have to multiply by 1024 each time instead of 1000. You can check out these powers using our powers calculator. For example, Mebi means 220. See the National Institute of Standards.