How Computer Bits and Bytes Abbreviations Work

Often, to make it easier to write large numbers, it is convenient to use abbreviations. Some of the most common abbreviations for large numbers include:

K = Kilo (1,000)
M = Mega (1,000,000)
G = Giga (1,000,000,000)
T = Tera (1,000,000,000,000).

In the future, it will become more common to use even larger numbers, so you can likely expect to see the following abbreviations in the future:

P = Peta (1,000,000,000,000,000)
E = Exa (1,000,000,000,000,000,000)
Z = Zetta (1,000,000,000,000,000,000,000)
Y = Yotta (1,000,000,000,000,000,000,000,000)

However, trying to use these abbreviations when dealing with computers, referring to bytes, is a little different.

The most common abbreviations used for bytes include:

8 bits = 1 byte
1,024 bytes = 1 KB
1,024 KB = 1 MB
1,024 MB = 1 GB
1,024 GB = 1 TB

In the future, as numbers grow larger and larger, we can expect to see the following abbreviations:

1,024 TB = 1 PT
1,024 PT = 1 ET
1,024 ET = 1 ZT
1,024 ZT = 1 YT

Usually the abbreviation name changes when the 1,000 limit is reached. For example 1,000 meters becomes 1 Kilometer, and 1,000 Kilometers will become 1 Megameter, and so on. For bytes, however, the abbreviation name changes when the 1,024 limit is reached. This is because of the numbering system that computers run on.

Normally, in any given NUMBER, each DIGIT has 10 possibilities (0,1,2,3,4,5,6,7,8,9), which can be called base 10. Computers, on the other hand, see each BIT (digit) of each BYTE (number) as either a 0 or a 1. So each bit has 2 possibilities (0,1), which can be called base 2. This is the main reason behind the 1,024 (rather than 1,000) milestone for each abbreviation.

The number 1 with a 0 added to the end becomes 10, and 10 with a 0 added to the end becomes 100, and so on. Each time a zero is added to the end, the number is multiplied by 10 (base 10). Similar to this, in base 2, a 1 with a 0 added to the end of it becomes 10 (which in base 10 is 2), and a 10 with a 0 added to the end becomes 100 (which in base 2 is 4), and so on.

We can use the number "1000" for some analysis. For the base 10 number 1000, the digits place increase with multiples of 10 (10⁰ = 1, 10¹ = 10, 10³ = 100, 10⁴ = 1000). For the base 2 number 1000, the digits place (bits place) increase with multiples of 2 (2⁰ = 1, 2¹ = 2, 2² = 4, 2³ = 8).

In base 2, the result of 2¹⁰ is 1,024, which is pretty close to 1,000 so it is called 1 KB. The result of 2²⁰ is 1,048,576 (1024 * 1024 aka 1,024 KB = 1 MB), which is pretty close to 1,000,000 so it is called 1 MB, and so on.

It could have been possible to just define 1,000 bytes as 1 KB, but when working with computer's machine language, it is easier to work in base 2, so the closest number to 1,000 when 2 is raised to some power is 2¹⁰ = 1,024. The difference between the actual number of bytes in a KB, MB, GB, etc and the apparent number of bytes when using rounded off estimates keeps getting larger and larger as the number increases.

So the next time you see a file that is 1 KB, remember, it is composed of not 1,000 bytes, but of 1,024 bytes!