How Big is a Byte?

Instructor: Martin Gibbs

Martin has 16 years experience in Human Resources Information Systems and has a PhD in Information Technology Management. He is an adjunct professor of computer science and computer programming.

How big is a byte? Is it a large chunk or just a little morsel? This lesson will provide an overview of bytes; what they are made of and how big they are.

Bits, Nybbles and Bytes

Bits, nybbles and bytes might sound like a brand of dog food, but the terms are used to describe the basic building-blocks of data in a computer. At their most basic level, computers only work with 1s and 0s; therefore all data is stored as such.

Before we get to bytes, we need to start with the smallest building block of data: the bit. A bit stores only a 1 or a 0. Think of an atom (we'll ignore all the subatomic particles for now); it is the building block of matter. The same is true with data. A bit (atom) makes up all data structures.

4 bits is a nybble. This is not a measure that is terribly useful, except to add some levity to a fairly technical subject (bits, bytes, 1s and 0s, machine language).

8 bits make up a byte.

Bit, Nybble, Byte
Bit Nybble Byte

How Big is a Byte?

A single byte is enough to hold a single typed letter, e.g., 'z' or 'A'. Since there are 8 bits in a byte, and a bit is either a 1 or a 0, the following is a representation of the letter A:


The number of possible patterns, or values, for a single byte is 256. This means that a byte can hold only a number between 0 and 255. The question is then: if the letter A is just one byte, and that byte can only be a number, how does the computer know to display the right value?

Enter ASCII, a standard for converting the numeric bytes to understandable characters.


ASCII stands for American Standard Code for Information Interchange. It is a 7-bit character code where each character is represented by a unique numeric value. ASCII codes range from 0 to 255, thus providing a mapping from the number-only format to something readable by humans.

Some letters are unique and take up two bytes: These are considered Unicode format, and are found in Greek, Arabic, or Mandarin language sets.

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