Number Base Converter

What this base converter does

Type a number into any one of the fields — decimal, hex, binary, octal, or a custom base you set yourself (anything from 2 to 36) — and every other field updates immediately. It uses BigInt math internally, so it stays exact even for numbers far larger than a normal 32-bit or 64-bit integer, and it handles negative values too.

How to use it

• Click into any of the four main fields and type or paste your number.
• Watch the other three update automatically — no convert button needed.
• Need something other than binary/octal/decimal/hex? Set the base in the Custom Base panel (2 through 36) and it stays synced with everything else.
• Use the copy buttons to grab the decimal, hex, or binary value straight to your clipboard.

Real-world use cases

Converting a hex color or memory address into decimal to debug it. Turning a decimal byte value into binary to understand a bitmask or flag. Working with older systems or file formats that use octal permissions or offsets. Base36 or other custom-base encodings sometimes used for compact IDs or short URL tokens.

Frequently asked questions

What's the difference between this and a scientific calculator's base conversion?

This tool shows every base at once and keeps them all live-synced, so you can see the same value in four representations simultaneously instead of converting one pair at a time.

Does it handle negative numbers?

Yes — enter a minus sign before the digits in any field and it carries through correctly to every other base.

Is there a limit on how large a number I can convert?

No practical limit — the converter uses arbitrary-precision BigInt arithmetic, so very large numbers stay exact instead of losing precision the way plain JavaScript numbers would.

What bases besides binary, octal, decimal and hex are supported?

Any base from 2 to 36 through the Custom Base field, using 0-9 then a-z as digits, which covers common encodings like base32 and base36.

Why would I need octal instead of hex?

Octal (base 8) still shows up in Unix file permission notation (like chmod 755) and in some older protocols and file formats, so it's useful to have alongside the more common hex and binary.