Number Base Converter

Free Number Base Converter — Binary, Octal, Decimal, Hexadecimal and More

Computers work in binary (base 2), programmers read memory in hexadecimal (base 16), Unix permissions use octal (base 8) and people count in decimal (base 10). A number base converter translates a value between these systems — and any other base from 2 up to 36.

Enter a number, choose the base it is written in, and see it in binary, octal, decimal, hexadecimal and base 36 at once, plus a custom base of your choice. It uses exact big-integer arithmetic, so even very long numbers convert without rounding errors, and it also shows the bit length.

Key features

How to use it

1. Type the number.
2. Select the base it is written in.
3. Read the equivalent in every other base.
4. Copy the value you need.

Worked example

Example

255 (decimal) = 11111111 (binary) = 377 (octal) = FF (hex)
FF (hex) = 255 (decimal)
1010 (binary) = 10 (decimal)

Who uses this tool

Tips for the best results

• Hex digits above 9 are A–F (case insensitive).
• Binary numbers only use 0 and 1.
• Count bits to see whether a value fits in 8, 16, 32 or 64 bits.
• Use base 36 for compact IDs.

Common mistakes to avoid

• Entering digits that do not exist in the chosen base (for example 2 in binary).
• Confusing decimal 10 with binary 10.
• Forgetting that leading zeros do not change the value.

Frequently asked questions