Number Base Converter — Binary, Octal, Decimal, Hex Online
Convert numbers between binary (base 2), octal (base 8), decimal (base 10), hex (base 16). BigInt support — unlimited digits. Optional digit grouping for readability.
1111 1111377255FFWhy use this tool
Type one number → see all 4 bases instantly. No pairwise converting.
Uses BigInt — convert numbers of any length, no Number.MAX_SAFE_INTEGER overflow.
Binary in nibbles (4), Hex in bytes (2), Decimal in thousands (3) — much faster to read.
How to use
- 1Enter the number.
- 2Pick the input base (binary / octal / decimal / hex).
- 3All 4 base outputs render in real time.
- 4Toggle 'Group digits' for readable formatting.
Number Base — When you need it
Base conversion is a daily dev chore: hex for color (#FF5733), binary for bitmask permissions (Unix octal 755), octal for file modes, hex for memory addresses, hex for hash output, binary for networking bitmaps. 0xFF = 255 = 0b11111111 is easy by hand; 0xDEADBEEF = ? needs a tool.
Uses JavaScript BigInt — no digit limit, so converting a UUID decimal (~38 digits) or sha256 hex (64 chars) all work. Web Crypto API hash output is Uint8Array but can be hex-stringified then pasted here to see in decimal/binary.
- ✓Binary (base 2)
- ✓Octal (base 8)
- ✓Decimal (base 10)
- ✓Hex (base 16) UPPERCASE
- ✓BigInt — unlimited digits
- ✓Digit grouping for readability
- ✓100% client-side
FAQ
Negative numbers?
Decimal accepts negative input. Binary/hex/oct rendering for negatives is two's complement? Current tool uses BigInt pure conversion — negatives just get a leading '-'.
Floating-point numbers?
Phase 1 is integer only. Float binary representation needs IEEE 754 — deferred to Phase 2 (as a separate 'Float Inspector' tool).
Group spaces mess up copy?
Toggle 'Group digits' off if you need raw copy. Each output box's copy button preserves the current format.