Octal to Decimal Converter

An octal to decimal converter turns an octal number into an everyday decimal number. Octal is base 8, so each digit is worth eight times the digit to its right. That place value idea is the whole conversion, and once you see it written out, octal to decimal becomes straightforward.

This converter shows every place value term, adds them up, and gives the exact decimal result. It is useful for computing study, file permissions and reading older code that uses octal values, and it works with no rounding and no sign up.

Everything runs in your browser, so your number never leaves your device. Enter an octal value, press Convert, and you can check the answer yourself from the steps shown.

Worked example: octal 52 to decimal

Write the place values from the right: the 2 sits in the ones place, worth 1, and the 5 sits in the eights place, worth 8.

Multiply each digit by its place value: 5 times 8 equals 40, and 2 times 1 equals 2.

Add the terms: 40 plus 2 equals 42. So 52 in octal is 42 in decimal.

The same method works for longer values: for 377, the terms are 3 times 64, plus 7 times 8, plus 7 times 1, which add up to 255.

How to Use This Tool

1. Enter an octal number using digits 0 to 7 only.
2. Press Convert to see the decimal result and the steps.
3. Copy the result or download it as a text file.
4. Use Load Sample to try 52, which converts to 42.

Why Use This Tool

• Exact for long octal values, with no rounding and no sign up.
• Shows every place value term, so the answer is easy to verify.
• Rejects digits 8 and 9 with a plain error message.
• Private by design, since nothing leaves your device.

Common Values

Related Conversions

If you need a different direction, try the Octal to Binary Converter, Octal to Hex Converter, Decimal to Octal Converter and Binary to Decimal Converter. Each one works the same way, in your browser, with the steps shown so you can check the answer.

Frequently Asked Questions