Octal to Decimal
Convert an octal number to its decimal (base-10) value.
About the Octal to Decimal converter
This tool converts an octal number into the everyday base-10 value people are used to. Each position in an octal number is a power of eight, so 32 means 3 times 8 plus 2, which is 26 in decimal. It is useful for making sense of octal values from file permissions, legacy code, or escape sequences when you want a familiar number.
How to use it
- Enter an octal number using only the digits 0 to 7.
- The decimal equivalent appears immediately.
- Copy the result for your notes, code, or calculations.
A common use is translating a permission digit, such as octal 7 meaning read, write, and execute, into a plain number. The converter treats the input as an unsigned whole number and handles long values exactly, so large numbers convert without rounding. Inputs containing an 8 or 9 are not valid octal. Everything runs in your browser, so the numbers you enter are never uploaded.
Frequently asked questions
How is octal converted to decimal?
Each octal digit is multiplied by a power of eight based on its position, then summed. For example octal 32 is 3 times 8 plus 2, which equals 26.
Why is my number rejected?
Octal allows only the digits 0 through 7. A digit of 8 or 9 makes the value invalid octal, so it will not convert.
Does it work with large octal numbers?
Yes. Exact integer arithmetic is used, so long octal values convert to decimal without precision loss.
Is the octal I enter uploaded anywhere?
No. The conversion happens in your browser, so your input stays on your device.