Direct answer
Paste a hex value below (with or without 0x prefix). The decimal equivalent appears instantly. 0xFF = 255, 0x100 = 256, 0xFFFFFF = 16,777,215.
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HEX input
Decimal output
About HEX → Decimal
Hexadecimal (base 16) is everywhere in computing — color codes (#FF0000), memory addresses (0x7fff5fbff8c0), file hashes, MAC addresses, and CPU registers. Converting to decimal is essential when you need to compare values, do arithmetic, or feed the number into something that expects base 10.
HEX vs Decimal
| HEX | Decimal | |
|---|---|---|
| Base | 16 (digits 0-9, A-F) | 10 (digits 0-9) |
| Prefix | 0x or # by convention | None |
| Use case | Memory, color, low-level | Everyday math |
| Bytes | 2 hex digits = 1 byte | Variable |
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Frequently asked questions
Why does 0xFF equal 255?
In hex, F is 15. So 0xFF = 15×16 + 15 = 240 + 15 = 255. This is also the maximum value of one byte (8 bits, 2^8 - 1).
Does case matter? Is 0xff the same as 0xFF?
No, case doesn't affect the value. By convention many systems use uppercase A-F for clarity, but parsers accept both.
What's the maximum value I can convert?
JavaScript safely handles integers up to 2^53 - 1 (about 9 quadrillion, or 0x1FFFFFFFFFFFFF in hex). Beyond that, precision is lost.