Octal Conversion Calculator

Work out octal conversion instantly with clear inputs, formula shown and shareable results.

About Octal Conversion Calculator

Octal uses base 8, so each digit maps to exactly three binary digits. That is why Unix file permissions are written in octal: each digit encodes the read, write and execute bits for one class of user.

Formula

Octal to decimal

value = Σ digitₖ × 8ᵏ

Worked example

With the default values below, Octal Conversion Calculator returns Octal of 755. Change any input above and every figure here is recalculated in your browser.

Inputs used

Value to convert: 755
Interpret the input asone of Octal (base 8), Decimal (base 10), Binary (base 2), Hexadecimal (base 16): Octal (base 8)

Results

Octal: 755
Decimal value: 493
Binary: 111101101
Unix permission reading: rwxr-xr-x

Step by step

1Values used
2Octal to decimal
3Octal= 755
4Decimal value= 493
5Binary= 111101101
6Unix permission reading= rwxr-xr-x

Assumptions and limits

The result is derived only from the 2 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to whole numbers, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

What does octal 755 mean?

493 in decimal, or rwxr-xr-x — full access for the owner and read plus execute for everyone else.

Why three bits per digit?

Because 8 = 2³, so each octal digit is exactly a group of three binary digits.