Number Base Converter
Convert any number between decimal, binary, hexadecimal, and octal instantly. Type a value into any field and the other three update automatically.
Type a value into any field below in decimal, binary, hexadecimal, or octal, and the other three update automatically. Useful for checking your work on byte values, color codes, memory addresses, or anything else that shows up in more than one base.
If you're still learning how to convert between bases by hand rather than just checking an answer, the number base conversion practice page walks through the method step by step and then quizzes you on it.
Why these four bases?
Decimal is what people use day to day. Binary is what the hardware actually stores — every value in memory is ultimately a sequence of 0s and 1s. Hex shows up constantly as shorthand for binary (colors, memory addresses, MAC addresses) because each hex digit maps to exactly 4 bits. Octal is less common today but still turns up in Unix file permissions and older systems, and maps just as cleanly to binary in groups of 3 bits.
Quick reference: 4-bit values
Since one hex digit always represents exactly 4 bits, memorizing this table makes converting between binary and hex a lookup instead of a calculation.
| Decimal | Binary | Hex |
|---|---|---|
| 0 | 0000 | 0 |
| 1 | 0001 | 1 |
| 2 | 0010 | 2 |
| 3 | 0011 | 3 |
| 4 | 0100 | 4 |
| 5 | 0101 | 5 |
| 6 | 0110 | 6 |
| 7 | 0111 | 7 |
| 8 | 1000 | 8 |
| 9 | 1001 | 9 |
| 10 | 1010 | A |
| 11 | 1011 | B |
| 12 | 1100 | C |
| 13 | 1101 | D |
| 14 | 1110 | E |
| 15 | 1111 | F |
Want to build this skill instead of just checking an answer? The number base conversion practice page explains the manual conversion methods step by step and then generates random problems for you to work through.