About hex and decimal

Hexadecimal is base 16 — digits 0–9 then a–f. One hex digit is exactly four bits, so bytes read as tidy two-digit pairs. Colors, memory addresses, and hashes are all conventionally written in hex with a 0x prefix.

Decimal is base 10 — ordinary numbers. Most code displays values in decimal even when they're stored as bits underneath, so it's usually one side of any base conversion.

For example, hex 7c3aed is 8141549 in decimal. The converter uses BigInt, so numbers of any size convert without losing precision — and it all runs in your browser.