Why do I need bases other than decimal?

Computers store everything in binary, but binary is unwieldy for humans to read, so hexadecimal (base 16) became the standard shorthand — each hex digit maps exactly to 4 binary bits, which is why you'll see hex in color codes, memory addresses, and MAC addresses. Octal (base 8) is less common today but still shows up in Unix file permissions.

How large a number can this handle?

This uses JavaScript's BigInt type internally, so it isn't limited by normal floating-point precision — it can accurately convert integers with dozens of digits, far beyond what a standard calculator's number type could handle without rounding errors.

What does a "custom base" mean?

Any base from 2 to 36, using digits 0–9 and then letters a–z for values 10 and above (so base 36 uses every digit and every letter). Base 36 is sometimes used to create short, URL-safe identifiers from large numbers, since it packs more value into fewer characters than decimal or hex.

Does this convert negative numbers or fractions?

No — it's built for positive whole numbers, which covers the vast majority of base-conversion needs (memory addresses, color values, IDs, permission bits). Negative numbers and fractional values use different representation rules (two's complement, fixed-point) that are outside the scope of a simple base converter.

BASE CONVERTER

Convert between binary, octal, decimal, hexadecimal, and any custom base from 2 to 36.

From base

Number

Binary	11111111
Octal	377
Decimal	255
Hexadecimal	ff

Custom base (2–36)

= 73

How to convert a number between bases

1
Choose the base your number is currently in: binary, octal, decimal, or hexadecimal.
2
Type the number — prefixes like 0x, 0o, and 0b are optional and stripped automatically.
3
Read the same value converted into every other base at once, or enter a custom base from 2 to 36.

Questions

Why do I need bases other than decimal?: Computers store everything in binary, but binary is unwieldy for humans to read, so hexadecimal (base 16) became the standard shorthand — each hex digit maps exactly to 4 binary bits, which is why you'll see hex in color codes, memory addresses, and MAC addresses. Octal (base 8) is less common today but still shows up in Unix file permissions.
How large a number can this handle?: This uses JavaScript's BigInt type internally, so it isn't limited by normal floating-point precision — it can accurately convert integers with dozens of digits, far beyond what a standard calculator's number type could handle without rounding errors.
What does a "custom base" mean?: Any base from 2 to 36, using digits 0–9 and then letters a–z for values 10 and above (so base 36 uses every digit and every letter). Base 36 is sometimes used to create short, URL-safe identifiers from large numbers, since it packs more value into fewer characters than decimal or hex.
Does this convert negative numbers or fractions?: No — it's built for positive whole numbers, which covers the vast majority of base-conversion needs (memory addresses, color values, IDs, permission bits). Negative numbers and fractional values use different representation rules (two's complement, fixed-point) that are outside the scope of a simple base converter.