Converts octal (base 8) values to decimal (base 10). Useful for interpreting Unix file permissions, understanding legacy computing notation, and working with programming languages that use octal literals. The tool accepts the 0o prefix optionally.
Octal to Decimal Converter
Convert octal (base 8) to decimal (base 10)
How to octal to decimal
- 1.Enter an octal number (digits 0-7 only) in the input field.
- 2.The decimal equivalent and all other bases appear instantly.
- 3.You can include the 0o prefix or leave it out.
- 4.Click Copy next to any result to use it.
About This Tool
Frequently Asked Questions
Multiply each octal digit by its positional power of 8, then sum the results. For example, 755 in octal = (7 x 64) + (5 x 8) + (5 x 1) = 493 in decimal.
In octal, 777 equals 511 in decimal. In Unix file permissions, chmod 777 grants read, write, and execute permissions to everyone.
The 0o prefix (zero followed by lowercase o) is used in JavaScript, Python, and other languages to indicate an octal literal, distinguishing it from decimal.