﻿ Octal Definition

# Octal

Octal, also known as "base-8," is a number system that uses eight digits (0 - 7) to represent any integer. Octal values are sometimes used to represent data in computer science since bytes contain eight bits. For example, the octal value "10" can represent 8 bits or 1 byte. "20" represents 2 bytes, 30 represents 3, etc. Octal values are also easily translatable from binary, which uses two digits, and hexadecimal, which uses 16 digits.

To convert an octal value to a standard decimal or "denary" value, multiply each digit by 8n, where n is the place of the digit, starting with 0, from right to left. Then add the results together. So 123 in octal can be converted to a decimal value as follows:

80 x 3 + 81 x 2 + 82 x 1 = 3 + 16 + 64 = 83

The table below shows several equal values in octal, decimal, hexadecimal, and binary:

1111
10881000
504028101000
10064401000000
123466829C1010011100

### Binary to Octal Conversion

To convert a binary value to an octal value, separate the digits into groups of three, starting from right to left. Then mulitply each 1 or 0 by 2n, where n is the place of each digit, from right to left, starting with 0. For example, to convert the binary value 1010011100 from the table above, first separate the digits as: 1 010 011 100. Then multiply the values as follows:

1. 0x1 + 0x2 + 1x4 = 4
2. 1x1 + 1x2 + 0x4 = 3
3. 0x0 + 1x2 + 0x4 = 2
4. 1x1 + 0x2 + 0x4 = 1

The resulting value is: oct 1234. Octal values may also be displayed with a subscript "8," such as 12348. The bottom row of the table above can be written in subscript notation as:

10100111002 = 12348 = 66810 = 29C16

Updated: March 12, 2021

Cite this definition:

https://techterms.com/definition/octal

#### TechTerms - The Tech Terms Computer Dictionary

This page contains a technical definition of Octal. It explains in computing terminology what Octal means and is one of many technical terms in the TechTerms dictionary.

All definitions on the TechTerms website are written to be technically accurate but also easy to understand. If you find this Octal definition to be helpful, you can reference it using the citation links above. If you think a term should be updated or added to the TechTerms dictionary, please email TechTerms!

Subscribe to the TechTerms Newsletter to get featured terms and quizzes right in your inbox. You can choose to receive either a daily or weekly email.