Number Base Converter radix
Convert numbers between binary, octal, decimal, hexadecimal, and any base from 2 to 36.
What this tool does
Computers work in binary, but binary is unreadable at length, so different bases are used depending on context. Hexadecimal packs four bits into one digit, expressing a byte in exactly two characters, which is why it dominates colour codes, memory addresses, hash values, and character codes. Octal groups three bits per digit and survives in Unix file permissions such as 755 and 644.
This tool converts a value into several bases at once. Binary, octal, decimal, and hexadecimal are always shown, and any additional base between 2 and 36 can be selected.
Arithmetic uses BigInt. Ordinary numbers lose precision beyond a certain magnitude, whereas BigInt has no digit limit and converts values larger than 64 bits exactly. That difference matters when handling large identifiers or long bitmasks.
When to use it
Use it to read a memory address or register value in decimal, to understand a permission value bit by bit, to translate a colour code into RGB numbers, to work out the value of each flag while designing a bitmask, or to read 0x literals from code in another language.
Input and output examples
255 in decimal
binary 11111111 / octal 377 / hex ff
The largest value a single byte can hold.
ff in hexadecimal
decimal 255
The conversion you need constantly when reading colour codes or memory values.
123456789012345678901234567890 in decimal
Exact conversion to hexadecimal with no lost digits
BigInt arithmetic keeps values beyond 64 bits accurate.
Notes and limitations
Input containing digits invalid for the selected base is rejected, such as a 2 in binary or a letter beyond f in hexadecimal. The 0x and 0b prefixes are handled automatically but produce an error if they contradict the chosen base. This tool works with integers only: fractional values are represented differently in each base and need separate handling. Negative values are shown with a leading sign, so if you need a two-complement representation you must decide on a bit width and calculate it separately.
Frequently asked questions
Do large numbers lose accuracy?
No. Conversion uses BigInt, so the value stays exact regardless of how many digits it has.
Can it convert fractional values?
This tool handles integers only. Fractions frequently become repeating expansions in another base and need their own rules.
What does permission 755 mean?
Three octal digits for owner, group, and others. 7 is binary 111, meaning read, write, and execute; 5 is 101, meaning read and execute.