Number Base Converter
Convert between binary, octal, decimal, hex and any base (2–36) at once — accurate for big integers via BigInt, all in your browser.
11111111377255ff1111 11118 Bit length100110🔒 Every conversion runs only in your browser.
Every base at once
Enter a number and its base to see binary, octal, decimal and hex results together. Enter 255 in decimal and you instantly get 11111111 and ff — handy for color codes, memory addresses and flag values.
Any base and bit length
Beyond the usual four, convert to any base from 2 to 36, and see the bit length plus a 4-bit grouped binary view — useful when studying bitwise operations or data structures.
Accurate for big numbers
Ordinary JavaScript numbers lose precision on large integers; this tool uses BigInt, so even values beyond 64 bits convert exactly. Negative numbers and underscore separators are accepted.
Frequently asked questions
How do I convert hex to decimal?
Set the input base to 16 and type a value like ff; decimal, binary and octal appear at once. Set the base to 10 to go the other way.
Is it accurate for very large numbers?
Yes. It computes with BigInt, so integers beyond 64 bits convert without precision loss.
Can I use bases other than 2–36?
The arbitrary-base field accepts 2 to 36; base 36 uses 0–9 and a–z.
Is my input stored?
No. Everything runs in your browser; nothing is uploaded or saved.