What Is Octet?
An octet is a unit used in computing to measure digital information. One octet is always equal to 8 bits. It is often the same size as what most people today call a byte. Using the word octet helps avoid confusion in places where the size of a byte might not be clear.
Definition
A bit is the smallest unit of digital information and can be 0 or 1. An octet is a group of 8 bits written together as one unit.
- 1 octet = 8 bits
- Each bit can be 0 or 1
- So 1 octet can show 256 different values from 0 to 255
In modern computers, a byte also usually has 8 bits. For this reason, in everyday use, octet and byte mean the same thing. However, the word octet is more exact because it always means 8 bits, while byte did not always mean that in older systems.
History / Origin
In the early days of computing, different computer systems did not always agree on the size of a byte. Some machines used 6 bit bytes, some used 7, some used 9, and others used 8.
Because of this, when people said byte, it was not always clear how many bits they meant. To solve this problem, the word octet was introduced. The word comes from Latin roots meaning eight. From the start, octet was defined as exactly 8 bits, without any doubt.
Telecommunications groups and international standards organizations liked this clear meaning. They began to use octet in technical rules and protocols, especially for networking and data communication. Over time, most modern computers started to use 8 bit bytes, so byte and octet became the same size in nearly all common systems.
Symbol & Abbreviation
The most common ways to write octet are:
- Full word: octet
- Short form in some languages and standards: o
In French speaking countries especially, you will often see:
- Ko for kilooctet instead of KB
- Mo for megaoctet instead of MB
- Go for gigaoctet instead of GB
People also use symbols for related units:
- b for bit
- B for byte
In most modern systems, 1 B equals 1 octet, but the symbol B officially means byte, not octet. The word octet is used when writers want to make it 100 percent clear that they are talking about 8 bits.
Current Use Around the World
Today, octet is widely used in technical areas where exact meaning is very important.
In networking and the internet
- Internet standards and many network protocols use octet instead of byte to avoid confusion.
- An IPv4 address, such as 192.168.0.1, is often described as 4 octets. Each number between the dots represents one octet and can go from 0 to 255.
- Email, web, and other internet standards documents from groups like the IETF often count data in octets.
In French speaking regions
- Storage sizes on packages and websites are often given in octets.
- You may see Ko, Mo, Go, which stand for kilooctet, megaoctet, and gigaoctet.
- In these places, octet is the everyday word that English speakers would usually call a byte.
In technical standards
- Some telecom and data communication standards use octet because they must be very exact.
- Programmers and network engineers use octet in documents and diagrams when they want to show that a field has exactly 8 bits.
Example Conversions
Here are some simple conversions that show how octets relate to bits, bytes, and larger units.
Between bits and octets
- 1 octet = 8 bits
- 2 octets = 16 bits
- 4 octets = 32 bits
- 8 octets = 64 bits
- 16 octets = 128 bits
Between octets and bytes
On almost all modern computers:
- 1 octet = 1 byte
- 10 octets ≈ 10 bytes
- 100 octets ≈ 100 bytes
- 1 000 octets ≈ 1 kilobyte or 1 kilooctet depending on language and context
Between octets and larger units
Using the simple decimal style that many storage makers use:
- 1 kilooctet (Ko) = 1 000 octets
- 1 megaoctet (Mo) = 1 000 000 octets
- 1 gigaoctet (Go) = 1 000 000 000 octets
Using the binary style that some operating systems and technical tools use:
- 1 kibioctet (Kio) = 1 024 octets
- 1 mebioctet (Mio) = 1 024 Kio = 1 048 576 octets
- 1 gibioctet (Gio) = 1 024 Mio ≈ 1.07 billion octets
In English, the binary versions are often written as kibibyte, mebibyte, gibibyte, and use the symbols KiB, MiB, GiB.
Related Units
Octets are part of a family of digital information units. Here are the most common related units.
- Bit (b)
Smallest unit of digital data. Can be 0 or 1. 8 bits make 1 octet. - Byte (B)
A unit of data used in computers. In nearly all modern systems, 1 byte = 8 bits, so 1 byte = 1 octet. In some very old systems, byte sizes were different, which is why the word octet became useful. - Kilooctet (Ko) or Kilobyte (KB)
Roughly one thousand octets or bytes, depending on the exact definition used. - Megaoctet (Mo) or Megabyte (MB)
Roughly one million octets or bytes. - Gigaoctet (Go) or Gigabyte (GB)
Roughly one billion octets or bytes. - Kibioctet (Kio) or Kibibyte (KiB)
Exactly 1 024 octets, used in binary based counting. - Mebioctet (Mio) or Mebibyte (MiB)
Exactly 1 048 576 octets. - Gibioctet (Gio) or Gibibyte (GiB)
Exactly 1 073 741 824 octets.
FAQs
Is an octet always 8 bits?
Yes. By definition, an octet is a group of exactly 8 bits. This never changes. That is the whole reason the word octet was created.
Is an octet the same as a byte?
On nearly all modern computers, 1 byte = 8 bits, so 1 byte = 1 octet. However, in some old systems, a byte did not always have 8 bits. Because of this history, technical documents sometimes use octet when they want to be extra clear that they mean 8 bits, not just a byte of unknown size.
Why do internet standards use octet instead of byte?
Internet and network standards must be very exact and must work on many different devices. Using the word octet makes it clear that all devices must use 8 bit units for that part of the protocol. This removes any risk of confusion about byte size.
What does 4 octets mean in an IP address?
An IPv4 address like 192.0.2.15 is made of 4 numbers separated by dots. Each of these four numbers is stored as one octet inside the computer. Since each octet can go from 0 to 255, this is why each part of an IPv4 address is in that range.
Why do some countries write Mo or Go instead of MB or GB?
In French speaking countries, the common word for a byte is octet. So they use Mo for megaoctet and Go for gigaoctet. In English speaking countries, people more often say MB and GB for megabyte and gigabyte, which are usually the same size.
How many different values can one octet hold?
One octet has 8 bits. Each bit has 2 possible values 0 or 1. So an octet has 2 to the power of 8 possible patterns, which equals 256. This means one octet can show any whole number from 0 to 255.
Where will I see the word octet in real life?
You may see it in networking lessons and books, in internet standards documents, on French language computer packaging, in operating system tools on French language settings, and in technical logs or diagrams made by network engineers.
