Kilobytes, megabytes and gigabytes are all used to denote storage capacity and file size. Using the base ten math system you're likely familiar with, it seems like 1000KB should equal 1MB, but a megabyte is actually 1024KB.
The Binary System
Data is measured using a base two binary system, instead of a base ten decimal system. The smallest measurement of data is a bit. A byte is eight bits and a kilobyte is 100 bytes, so it is equal 1024 bytes. Following the same pattern, a MB is 1024KB and a GB is 1024MB. See the Resources below for a data measurement reference chart.
Online conversion calculators enable you to quickly convert, for example, KB to GB, or MB to GB. See the Resources below for a number of data measurement conversion calculators.