Hex to Decimal Converter

Because hex is the most compact notation that lines up cleanly with binary. Every hex digit covers exactly four binary bits (since 2^4 = 16), so two hex digits represent one 8-bit byte and four digits cover a 16-bit word. A 32-bit register is eight hex digits long instead of thirty-two binary digits, which is much easier to read and proofread. Decimal does not share that clean mapping with binary, so any time you need to see bit patterns (memory addresses, color channels, status flags, machine code) hex is the natural display format.

In four places that come up daily for developers and designers. Memory addresses (debuggers and stack traces print pointers as 0x7ffeefbff5c8). CSS and design colors (#FF5733 is three byte-sized channels for red, green, and blue). MAC addresses (00:1A:2B:3C:4D:5E uses six hex bytes to identify a network interface). And source code: C, C++, Java, JavaScript, Python, Rust, and Go all use the 0x prefix to write integer literals in hex (0xFF, 0xDEADBEEF), which is faster to type and read than the equivalent decimal when the value is meant to be a bit pattern.

Hex needs sixteen distinct digits, so after 0-9 it borrows the first six letters: A = 10, B = 11, C = 12, D = 13, E = 14, F = 15. From there it works exactly like decimal, only each position is worth a power of 16 instead of a power of 10. The digit F in the rightmost position is 15. The same F one place left is 15 x 16 = 240. So FF = 15 x 16 + 15 = 255, which is the largest value a single byte (eight bits) can hold.

The 0x prefix tells a parser that the following digits are hexadecimal. For example, 0xFF means 255 in decimal. Outside source code, context often makes the base clear, so color values, MAC addresses, and hash digests usually omit the prefix. This converter accepts input with or without 0x.

The value is identical: FF, Ff, fF, and ff all mean 255. The convention is mostly stylistic. Uppercase A-F is more common in low-level contexts like assembly listings, hex dumps, debuggers, and most C-family code (and is what RFC 4648 recommends for the standard base-16 encoding). Lowercase a-f is the norm in CSS colors (#ff5733), URLs, and many hash representations. The converter accepts either case on input and lets you pick the case for the output so you can match the style guide of whatever you are pasting into.