Hex to Decimal Converter

Hexadecimal, or hex, writes numbers with sixteen digits: 0 to 9, then A for 10, B for 11 and so on up to F for 15. Each place is worth 16 times the place to its right, so to get the decimal value you multiply every digit by 16 to the power of its place, counted from zero on the right, and add up: FF is 15 × 16 + 15 = 255, and 7E5 is 7 × 256 + 14 × 16 + 5 = 2021. Type or paste one number per line, and the decimal values appear as you type. The prefixes 0x and #, as in 0xFF or #FF, are understood, small and capital letters both work, and spaces or underscores between groups of digits are ignored.

The converter is exact for whole numbers of any length, far beyond the 16 digits where a calculator or a spreadsheet starts to round, so the 64-bit value FFFFFFFFFFFFFFFF gives 18446744073709551615. Negative numbers and fractions work too: A.8 is 10.5. Under the result, the converter shows how the first number is calculated, step by step, which helps with homework and checks. Use “From” and “To” for binary, octal or any base from 2 to 36, and “Swap” to convert the decimal results back to hex. “Group digits” writes long results in groups of three, as in 16 777 215.