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Convert numbers between binary, octal, decimal, and hexadecimal in real time.
Quick Reference (0-15)
| Dec | Bin | Oct | Hex |
|---|---|---|---|
| 0 | 0000 | 0 | 0 |
| 1 | 0001 | 1 | 1 |
| 2 | 0010 | 2 | 2 |
| 3 | 0011 | 3 | 3 |
| 4 | 0100 | 4 | 4 |
| 5 | 0101 | 5 | 5 |
| 6 | 0110 | 6 | 6 |
| 7 | 0111 | 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 |
Type a number in any of the four fields - binary, octal, decimal, or hex.
The other three fields update automatically as you type.
Click the copy icon next to any field to copy that value.
A number base converter changes a number between numeral systems: binary (base 2), octal (base 8), decimal (base 10), hexadecimal (base 16), and any base from 2 to 36. Enter a value in one base and read it in all the others instantly.
Binary, hex, and decimal are the currencies of programming: memory addresses in hex, flags in binary, counts in decimal. Converting between them by hand is error-prone, so a converter that shows every base at once removes the mistakes.
Decimal is for humans and counts. Binary (base 2) is how hardware stores everything, one bit per digit, so it shows bit flags and masks directly. Hexadecimal (base 16) is shorthand for binary: one hex digit equals exactly four bits, so a byte is two tidy hex digits. That is why colors, memory addresses, and byte dumps are written in hex rather than long binary strings.
Every base expresses the same quantity with a different set of digits and place values. Decimal 255 is 11111111 in binary and FF in hex: three notations for one number. Converting means re-expressing the value's magnitude in the target base's digits, which is pure arithmetic with no rounding, so conversions between integer bases are always exact.
Because 16 is 2 to the fourth power, each hexadecimal digit maps to exactly four binary digits with no overlap. F is 1111, A is 1010, and so on. This is why programmers read hex fluently: it is binary compressed four bits at a time, far easier to scan than a wall of ones and zeros while representing the same bits exactly.
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