Convert Numbers Between Any Base
Enter a number and instantly see it in binary, octal, decimal, hexadecimal, and any custom base from 2 to 36.
About the Number Base Converter
This tool converts whole numbers between binary, octal, decimal, hexadecimal, and any custom base from 2 to 36, all at once and all in your browser. It uses JavaScript's BigInt under the hood, so there's no limit on how large a number you can convert — unlike calculators that break down past 32 or 64 bits. Auto-detect mode reads standard 0x, 0b, and 0o prefixes, and negative numbers are fully supported.
Features:
- Arbitrary precision via BigInt — no overflow on huge numbers
- Auto-detects 0x, 0b, and 0o prefixes, plus negative numbers
- Custom bases from 2 to 36 for both input and output
- Binary output grouped in readable nibbles (1010 1100)
How to Convert a Number
- Type or paste a number into the input field
- Choose its base — or leave it on Auto to detect 0x/0b/0o prefixes
- See it instantly converted to binary, octal, decimal, and hex
- Pick a custom base from 2–36 and copy any row you need
Frequently Asked Questions
What number bases does this tool support?
Binary (base 2), octal (base 8), decimal (base 10), and hexadecimal (base 16) are always shown, plus a custom base you can set anywhere from 2 to 36 for both input and output.
How do I enter a hexadecimal or binary number?
Select the matching base from the dropdown, or leave it on Auto and type the number with its standard prefix: 0x for hex, 0b for binary, and 0o for octal — for example 0xFF, 0b1010, or 0o17.
Can this tool handle negative numbers?
Yes. Start the number with a minus sign (e.g. -1F in hex or -101 in binary) and every output base will show the same signed value.
Why can I convert numbers bigger than other tools allow?
This converter uses JavaScript's native BigInt type instead of regular 32-bit or 64-bit integers, so there's no upper limit on precision. Most calculator apps and spreadsheet formulas silently overflow or round once a number outgrows their fixed bit width; this tool keeps every digit exact no matter how large the number is.
What does the digit-count / bit-length row tell me?
It shows how many bits the number needs in binary and how many digits it has in decimal, which is useful for sizing data types, checking storage requirements, or verifying a value fits a fixed-width field.
Why is hexadecimal used so much in programming?
Hex is a compact, human-friendly stand-in for binary: each hex digit represents exactly four bits (a nibble), so converting between the two is simple and lossless. This makes hex the standard way to write memory addresses, color codes, byte values, and binary data dumps.
Privacy First
All conversion happens locally in your browser using JavaScript. Your numbers are never uploaded, transmitted, or stored on any server.