What is a number base?
A number base is simply how many distinct digits a system uses before it rolls over to the next place. We count in decimal (base 10) using digits 0–9. Computers work in binary (base 2), using only 0 and 1, because that maps neatly to “off” and “on” in circuits. Hexadecimal (base 16) uses 0–9 then A–F, giving a compact way to write bytes and colours, and octal (base 8) uses 0–7. This tool converts a number between all four at once.
How to convert
- Type your number.
- Choose which base you entered it in.
- See it instantly in binary, octal, decimal and hexadecimal, and copy any result.
Where each base shows up
- Binary: the raw language of computers and bitwise operations.
- Hexadecimal: colour codes (
#ff8800), memory addresses and byte values. - Octal: Unix file permissions (like
chmod 755). - Decimal: everyday human counting.
Frequently asked questions
Can I paste prefixes like 0x or 0b? Yes — 0x, 0b and 0o prefixes are ignored automatically.
Why does hex use letters? Base 16 needs 16 symbols, so after 0–9 it borrows A–F to represent 10–15.
Is it private? Yes — conversion happens entirely in your browser.