A unit prefix is a group of letters attached to the beginning of a unit of measurement. You’re probably familiar with unit prefixes for measurements, such as the meter. For example, the prefix “kilo” can be added to the meter to form a kilometer, a unit of length equivalent to 1000 meters. A kilogram is a unit of weight equivalent to 1000 grams.
In these examples, the prefix multiplies the base unit by a power of 10 (1000 = 10^{3}). With units of digital information, such as the byte, these prefixes actually multiply the base by a power of two. This is because the byte is made of binary digits (binary meaning two).
EXAMPLE
When adding the prefix kilo to byte, we get the kilobyte. A kilobyte is defined as 2^{10} or 1024 bytes. This can be confusing, especially since we are familiar with multiplying other measurements by 1000, not 1024, when applying the prefix kilo. Due to this confusion, it has become common and acceptable to round 1024 to 1000 when applying prefixes to bytes.Recall that a byte is a unit of digital data, consisting of binary digits made of 0s and 1s. When dealing with millions and billions of bytes, it is easier to express the size of the data using binary prefixes. The most common binary prefixes are kilobyte, megabyte, and gigabyte. In today’s society, the terabyte is also becoming more popular to describe machines with very large storage capacities.
Prefix | Notation | Represents | Example |
---|---|---|---|
kilo | KB | 1 thousand | 1 KB = 1,000 bytes |
mega | MB | 1 million | 1 MB = 1,000,000 bytes |
giga | GB | 1 billion | 1 GB = 1,000,000,000 bytes |
tera | TB | 1 trillion | 1 TB = 1,000,000,000,000 bytes |
EXAMPLE
A brief email of text would be one to two kilobytes. A larger file, such as a minute-long video clip, would be 15 to 20 megabytes. Today’s smartphones can have capacities of 64 gigabytes or more. A professional videographer might need a hard drive with one terabyte to store the multimedia files and software programs she needs to do her job.Rank the following storage sizes from smallest to largest: 5KB, 1TB, 6MB, 3GB.
What did you come up with? To solve this, it is helpful to write each measurement in one unit, such as bytes, and then compare:
5KB= 5,000 bytes
1TB= 1,000,000,000,000 bytes
6MB= 6,000,000 bytes
3GB= 3,000,000,000 bytes.
So, the correct ordering of these, from smallest to largest, would be 5Kb, 6MB, 3GB, 1TB
Hertz is a unit of frequency named after German physicist Heinrich Hertz. This unit of frequency is defined as one cycle per second, and is used to describe the processing speed of computing devices. Hertz is abbreviated Hz, and can also be used with the prefixes mentioned above.
Prefix | Notation | Represents | Example |
---|---|---|---|
kilo | KHz | 1 thousand | 1 KHz = 1,000 hertz |
mega | MHz | 1 million | 1 MHz = 1,000,000 hertz |
giga | GHz | 1 billion | 1 GHz = 1,000,000,000 hertz |
tera | THz | 1 trillion | 1 THz = 1,000,000,000,000 hertz |
EXAMPLE
The speed of today’s desktop and mobile processors are measured in gigahertz (GHz) and can range from two to four GHz.Source: Derived from Chapter 2 “Information Systems for Business and Beyond” by David T. Bourgeois. Some sections modified for brevity. https://www.saylor.org/site/textbooks/Information%20Systems%20for%20Business%20and%20Beyond/Textbook.html