Octal to Decimal Converter

Octal is the base-8 number system, using digits 0–7. Because each octal digit maps exactly to 3 binary bits, it was historically popular for compactly displaying binary data on systems with word sizes divisible by 3. Today its main practical use is Unix/Linux file permissions, expressed as three-digit octal numbers like 755.

Decimal is the base-10 number system used in everyday counting, built from the digits 0–9. It's the format humans read and reason about naturally, which is why programmers convert binary, octal, and hexadecimal values back to decimal whenever they need a human-readable number.

To convert octal to decimal, multiply each digit by its positional power of 8 (starting from 1 on the right) and add the results. For example, octal 12 = (1×8) + (2×1) = 10. The same method turns 312 into (3×64)+(1×8)+(2×1) = 202.