Number Base Converter
Convert numbers between binary, octal, decimal, and hexadecimal instantly.
About the Number Base Converter
Programmers meet the same number in four costumes: decimal in everyday code, hexadecimal in colors and memory addresses, binary in flags and bitmasks, octal in Unix file permissions. This tool converts between all four at once. Type a number, pick which base it is in, and read off the others.
It handles arbitrarily large numbers (using big integer math, not floating point), accepts the conventional prefixes 0x, 0b, and 0o, and ignores spaces and underscores used as digit separators.
Typical uses: turning a hex color channel into its decimal value, reading what bits are set in a flags field, converting a chmod value, and checking what that hex constant in someone else's code actually equals.
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Frequently asked questions
Why does hexadecimal use letters?
Base 16 needs sixteen digit symbols and we only have ten numerals, so a through f represent 10 through 15. Two hex digits exactly represent one byte (0 to 255), which is why hex is everywhere in computing.
How large can the numbers be?
Effectively unlimited. Conversion uses big integer arithmetic, so numbers far beyond the usual 64 bit limit convert exactly, with no rounding.
Does it handle negative or fractional numbers?
No, whole non negative numbers only. Negative numbers in binary involve representation choices (two’s complement width) that depend on the system, and fractional bases are a different problem entirely.