Number Base Converter
Convert numbers between binary, octal, decimal and hexadecimal.
Type a value in any field - decimal, hexadecimal, octal or binary - and the other three update instantly. Works with bigints, so no precision limits for typical use.
How to use it
Type in any field
Decimal, hex, octal or binary.
Read the others
All four fields update on every keystroke.
Copy what you need
Copy button next to each field.
What is it?
A number base converter translates a value between positional numeral systems. Decimal (base 10) is what humans use; binary (base 2) is the native language of hardware; hexadecimal (base 16) is the compact form developers use for colours, memory addresses and bit-mask flags; octal (base 8) appears in Unix file permissions.
When to use it
Reading a hex colour code as RGB components; converting Unix file modes between octal and binary bit flags; debugging a binary protocol; turning a memory address from hex into decimal for a script; or simply checking your homework.
Common mistakes
Forgetting the 0x / 0o / 0b prefixes when pasting into a programming language - they matter to a parser. Mixing signed and unsigned representations for negative values. And confusing little-endian vs big-endian byte order: this converter operates on numeric values, not byte buffers.
FAQ
- What's the largest number supported?
- Arbitrary - we use JavaScript bigints, so a 1000-digit decimal still converts exactly. Floating-point values are not supported here.
Rate this tool
Share your experience to help others.