Number Converter
A number converter between four major numeral systems: binary (BIN), octal (OCT), decimal (DEC), and hexadecimal (HEX). Enter a number in any field — the others will update instantly. Supports arbitrarily large numbers via BigInt.
Numeral Systems in Programming Binary (base 2) is the foundation of computer operation — all data at the processor level is represented as zeros and ones. Octal (base 8) is used in Unix for file permissions (e.g., chmod 755). Hexadecimal (base 16) is used for memory addresses, CSS color codes (#FF5733), and byte representation.
Free online number converter between four major numeral systems: binary (BIN), octal (OCT), decimal (DEC), and hexadecimal (HEX). Enter a number in any of the four fields — the others will update instantly.
Binary (base 2) is used in computers for data representation at the processor level. Octal (base 8) is used in Unix systems for file permissions. Decimal (base 10) is the standard system for everyday calculations. Hexadecimal (base 16) is widely used for memory addresses, CSS color codes, and byte representation.
The converter uses JavaScript BigInt, ensuring correct operation with arbitrarily large numbers without loss of precision. Input is validated in real time: only characters valid for the selected numeral system are accepted. Useful for programmers, students, and anyone working with bitwise operations and low-level data structures.
How to use it
- Type a number into any of the four fields: binary, octal, decimal or hexadecimal.
- The other fields update instantly. The 0b, 0o and 0x prefixes are recognised automatically and hex is case-insensitive.
- Numbers of any length are handled exactly thanks to BigInt — no overflow or precision loss.
When it helps
- Programming: turn a mask like 0xFF or a flag like 0b1010 into a readable decimal value and back.
- Networking and permissions: map a subnet mask to bits or understand octal chmod 755.
- Study: check homework on number systems and see how a value looks in each base.
Frequently asked questions
Are negative and fractional numbers supported?
Negative — yes, with a normal minus sign. Fractional — no: the converter works with integers, like most programming tasks.
Why is hexadecimal so common?
One hex digit is exactly four bits, so a byte is written with two characters: 0xFF = 11111111. It is more compact than binary and easy to convert in your head.
Where is octal used?
Mainly in Unix permissions (chmod 644, 755) and a few legacy formats. Each octal digit is three bits: read, write, execute.