Number Base Converter
Convert between binary, octal, decimal, hexadecimal and any base from 2 to 36, with big numbers.
Type a number and the results update as you type.
- Binary (base 2)
- Octal (base 8)
- Decimal (base 10)
- Hexadecimal (base 16)
- Custom
How this converter works
Pick the base your number is written in, type it, and the tool rewrites it in binary, octal, decimal, hexadecimal and any custom base from 2 to 36 at the same time. Parsing uses JavaScript BigInt, so there is no 53-bit ceiling: a 256-bit hash, a 64-bit database ID or a 100-digit decimal converts exactly, digit for digit. Prefixes such as 0b, 0o and 0x are accepted when they match the chosen base, underscores and spaces are ignored as separators, and a leading minus sign is carried through to every output. Digit grouping is a display option only; the copy buttons still copy the grouped text you see.
Quick reference: 0–16
| Decimal | Binary | Octal | Hex |
|---|---|---|---|
| 0 | 0 | 0 | 0 |
| 1 | 1 | 1 | 1 |
| 2 | 10 | 2 | 2 |
| 3 | 11 | 3 | 3 |
| 4 | 100 | 4 | 4 |
| 5 | 101 | 5 | 5 |
| 6 | 110 | 6 | 6 |
| 7 | 111 | 7 | 7 |
| 8 | 1000 | 10 | 8 |
| 9 | 1001 | 11 | 9 |
| 10 | 1010 | 12 | A |
| 11 | 1011 | 13 | B |
| 12 | 1100 | 14 | C |
| 13 | 1101 | 15 | D |
| 14 | 1110 | 16 | E |
| 15 | 1111 | 17 | F |
| 16 | 10000 | 20 | 10 |
Notes and tips
- Letters in bases above 10 follow the usual convention: A = 10, B = 11 … Z = 35. Input is case-insensitive; output uses upper case.
- A digit that is too large for the chosen base is reported with its position, so a stray 8 in an octal value or a G in a hex value is easy to spot.
- Only whole numbers are converted. Fractions and exponents are not supported, and negative values are shown with a minus sign rather than two’s complement.
- Grouping follows common habits: binary in nibbles of 4, hexadecimal in bytes of 2, octal in threes and decimal with a comma every three digits.
Privacy
Conversion happens in your browser with no server involved. Nothing you type is uploaded or stored, and the page keeps working offline once loaded.