Number Base Converter
| Base | Value |
|---|
Any other base
What a base actually is
The base is how many digits are available before you carry. Decimal has ten, so after 9 comes 10. Binary has two, so after 1 comes 10 — the same idea, fewer symbols. Nothing about the quantity changes; only how it is written.
The bases you meet
- Binary (2) — what the machine actually stores.
- Octal (8) — Unix file permissions, where 755 is three groups of three bits.
- Decimal (10) — everyday counting.
- Hexadecimal (16) — colours, memory addresses, byte dumps.
- Base 36 — short identifiers, using every digit and letter.
Why big numbers go wrong elsewhere
Most converters use ordinary JavaScript numbers, which lose precision beyond about 9 quadrillion — the last digits silently change. This one uses BigInt, so a 200-digit value converts exactly.
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Frequently Asked Questions
As large as you like. The arithmetic uses BigInt, so a 200-digit number converts exactly. Ordinary JavaScript numbers lose precision above about 9 quadrillion, which is why many converters quietly give wrong digits on long values.
Once the digits 0 to 9 run out, letters continue the count: A is 10, B is 11, up to F for 15. Base 36 carries that all the way to Z for 35.
Because one hex digit is exactly four binary digits, so a byte is always two hex characters. Reading FF is far easier than 11111111, and the mapping is exact rather than approximate.
Yes, with a leading minus sign. It does not do two's complement — that depends on a word size, so 8-bit and 32-bit answers would differ, and guessing which you meant would be worse than not offering it.
Yes. A 0x, 0b or 0o prefix is recognised and the base is set for you, so pasting straight from code works.