Hex to Decimal Converter
Convert hexadecimal to decimal and back instantly, with binary, octal and batch conversion.
Hex to decimal
- Binary
- —
- Octal
- —
- Bit length
- —
Decimal to hex
Batch convert (one hex value per line)
How it works
Type a hexadecimal number and the decimal value appears instantly, together with its
binary and octal form and how many bits it needs. Hex is base 16, so each digit is worth
16 times the one to its right: FF is 15 × 16 + 15 = 255, the largest value a
single byte can hold. Prefixes and separators are optional — 0x1A,
#1a and 1A all convert to 26 — and the decimal-to-hex box works
the other way round, with switches for uppercase digits and a 0x prefix.
Conversion uses JavaScript's arbitrary-precision BigInt maths, so colour codes, 64-bit hashes and hex values hundreds of digits long convert exactly, with no rounding and no floating-point drift. The batch box converts a whole list at once and lets you copy or download the results as a text file. Everything runs 100% in your browser: unlike converters that post your values to a server, nothing you paste here is uploaded, logged or shown an ad. Need base 2, 8, 36 or anything in between? Use the number base converter linked below.
Frequently asked questions
How do you convert hex to decimal?
Multiply each hex digit by 16 raised to its position, counting from 0 on the right, then add the results. For FF that is 15 × 16 + 15 × 1 = 255. Paste the value above and the converter does the arithmetic for you, showing the decimal, binary and octal forms at once.
What is FF in decimal?
FF in hexadecimal is 255 in decimal. It is the largest value one byte (8 bits) can hold, which is why colour channels and byte values top out at FF — the colour #FFFFFF is 255, 255, 255, or pure white.
Can this converter handle very large hex numbers?
Yes. It uses JavaScript's arbitrary-precision BigInt arithmetic, so 64-bit values, hashes and hex strings hundreds of digits long convert exactly with no rounding or floating-point drift — unlike converters that lose precision above 2^53.