DocomintConvertisseur de Base Numérique
Convertissez des nombres entre binaire, octal, décimal, hexadécimal, ou toute base de 2 à 36.
What is a Convertisseur de Base Numérique?
Converts a number between any two bases from 2 (binary) to 36 (using 0-9 then A-Z as digits), not just the common binary/octal/decimal/hex set — useful for debugging a bitmask, reading a color code, or checking a base-36 short-URL ID by hand.
How to use the Convertisseur de Base Numérique
- Enter a value and its current base
- Enter the base to convert it to
- The converted value appears instantly, computed on your device
Formula
Decimal value = Σ (digit × baseᵖᵒˢⁱᵗⁱᵒⁿ); converting back uses repeated division by the target base
Every conversion between two arbitrary bases routes through decimal (base 10) as an intermediate step internally.
Example
The decimal number 255 converts to FF in base 16 (hexadecimal) — the maximum value a single byte can hold, and the reason 0xFF shows up constantly in color codes and bitwise flags.
Common mistakes
- Using a digit that's invalid for the source base — entering a "9" while converting from binary (base 2), which only allows 0 and 1.
- Assuming uppercase and lowercase letter digits (for bases above 10) are treated differently — this tool treats "a" and "A" identically.
- Expecting leading zeros to be preserved in the output — they're dropped, the same way "007" and "7" are the same number.
Frequently asked questions
What are different number bases actually used for?
Binary (base 2) is how computers represent data at the hardware level. Hexadecimal (base 16) is a compact, human-readable way to write binary values — used constantly in color codes (#FF5733), memory addresses, and bitwise flags. Octal (base 8) shows up in Unix file permissions.
How do I convert hexadecimal to decimal?
Set the from-base to 16 and the to-base to 10. Each hex digit (0-9, then A-F for 10-15) is multiplied by 16 raised to its position and summed — this tool does that conversion for you instantly.
What letters represent digits above 9?
A through Z represent 10 through 35, in order — so base 16 (hex) uses 0-9 and A-F, and base 36 (the maximum supported here) uses the full 0-9 and A-Z range.
Is there a limit on how large a number I can convert?
Yes — values are capped at JavaScript's safe integer range (about 9 quadrillion in decimal). A larger value returns an error rather than a silently rounded result.
Is my numbers uploaded anywhere?
No — Convertisseur de Base Numérique runs entirely in your browser using JavaScript/WebAssembly. Your numbers is never sent to a server.