Number Base Converter
Convert numbers between binary, octal, decimal, hexadecimal and any base from 2 to 36 — instantly, with support for huge integers.
About the Number Base Converter
This number base converter translates a value from any base into binary, octal, decimal and hexadecimal simultaneously — plus a custom output base of your choice from 2 to 36. Type a number, pick which base it's written in, and every representation appears at once with its own copy button. Prefixes like 0x, 0b and 0o are accepted automatically.
Different bases are just different ways of writing the same quantity. Computers store everything in binary (base 2), programmers read memory addresses and colors in hexadecimal (base 16) because one hex digit maps to exactly four bits, and octal survives in Unix file permissions. Decimal is simply the base-10 system humans grew up with.
Unlike many converters that silently lose precision past 15–16 digits, this tool uses arbitrary-precision integers (BigInt), so 64-bit values, hashes and other huge numbers convert exactly. Input is validated against the selected base, so a stray digit — like an 8 in octal — is flagged immediately instead of producing a wrong answer.
How to Use the Number Base Converter
- 1Type the number you want to convert.
- 2Select the base it's currently written in — binary, octal, decimal, hex, or a custom base 2–36.
- 3Read the binary, octal, decimal and hexadecimal results instantly.
- 4Set a custom to-base if you need something else, and copy any result with one click.
Frequently Asked Questions
How do I convert binary to decimal?
Each binary digit is a power of two, read right to left: 1101 is 1×8 + 1×4 + 0×2 + 1×1 = 13. In this tool, just set the from-base to binary and type the digits — the decimal (and octal and hex) equivalents appear instantly. Going the other way, repeatedly divide the decimal number by 2 and read the remainders bottom-up.
What is FF in decimal?
Hexadecimal FF equals 255 in decimal: F is 15, so FF is 15×16 + 15 = 255. It's the largest value a single byte (8 bits) can hold, which is why 255 shows up everywhere in computing — RGB color channels run 0–255, and IPv4 address octets max out at 255.
Why do programmers use hexadecimal instead of binary?
One hex digit represents exactly four binary bits, so a byte is always two hex digits — 11111111 becomes FF. That makes hex a compact, human-readable shorthand for binary data: memory addresses, color codes like #FF5733, MAC addresses and hash digests are all conventionally written in hex rather than long strings of 0s and 1s.
Can this converter handle numbers bigger than 2^53?
Yes. JavaScript's ordinary numbers lose integer precision above 9,007,199,254,740,991 (2^53 − 1), but this tool parses and formats with BigInt, which has no fixed limit. You can convert 64-bit values, 256-bit hashes or arbitrarily long integers between bases with exact results.
What does base 36 look like?
Base 36 uses all ten digits 0–9 plus the 26 letters a–z, so it's the largest base with a natural alphanumeric alphabet. It packs numbers into short case-insensitive strings — 1,000,000 is only "lfls" — which is why base 36 is popular for short URLs, invite codes and compact database IDs.