Binary to Text (ASCII) Converter

How binary becomes text

Computers store text as numbers, and numbers as bits. In the ASCII code, every character has a number from 0 to 127, written in binary as one byte of eight bits:

To read binary by hand, split it into bytes, convert each byte from base 2 — 01001000 is 64 + 8 = 72 — and look up the character. The converter does this for every byte and lists the codes in a table, so you can check each step.

Spaces, missing bits and long runs

Binary is easiest to read with a space between bytes, but it is often copied as one long run. If the number of bits is a multiple of eight, the converter splits the run into bytes; if not, it tells you how many bits it found, which usually means one is missing or doubled. Groups shorter than eight bits are read as numbers too, so 1001000 1101001 still spells Hi — the leading zero is just left off.

ASCII and UTF-8

ASCII covers 128 characters: the English alphabet, digits, punctuation and control codes, defined in the 1960s and documented for the internet in RFC 20. UTF-8, the encoding used by almost every web page today, keeps those 128 characters as the same single bytes and adds every other Unicode character in two to four bytes: é is 11000011 10101001, € is three bytes and most emoji four. Choose UTF-8 for anything beyond plain English text; choose ASCII to check that a message uses only ASCII characters — bytes above 127 are flagged.

Reading binary by hand

Each bit in a byte has a place value, doubling from right to left: 128, 64, 32, 16, 8, 4, 2, 1. Add the values of the bits that are 1: in 01101001 those are 64, 32, 8 and 1, which make 105 — the letter i. Capital letters run from 65 (A) to 90 (Z) and small letters from 97 (a) to 122 (z), so the third bit from the left, worth 32, is the only difference between a capital and a small letter.

Text to binary

Switch the direction to encode text: each character becomes its UTF-8 bytes, shown in binary, hexadecimal and decimal. “Hi” is 01001000 01101001, two bytes or 16 bits. For converting numbers between bases or doing arithmetic with powers of two, the scientific calculator helps; for storage sizes in bytes, kilobytes and gigabytes, see KB to GB; and for a random byte or number, the random number generator.