Text to Binary Converter
Eight bits per ASCII character, with the code points shown alongside.
How a character becomes eight ones and zeros
In ASCII, every character has a number, and every number is written in binary with eight digits. A is 65, which is 01000001; a is 97, 01100001. The high bit distinguishes the two: uppercase letters occupy 65–90, lowercase 97–122, and digits 48–57. A single flipped bit between 65 and 97 — which is exactly 01000001 versus 01100001 — is why case-insensitive comparison in ASCII is a bitmask, not a table lookup.
ASCII is 7 bits; text is not
ASCII defines only 128 code points, all representable in seven bits. Anything outside A–Z a–z 0–9 and basic punctuation needs more. In UTF-8, a character uses one byte if it is ASCII, two bytes for most European letters with accents, three for the majority of CJK characters, and four for emoji and rare scripts. So A is 01000001 (8 bits) while 中 is 11100100 10111000 10101101 (24 bits), and 🚀 is four bytes, 32 bits.
| Character | Code point | UTF-8 bytes | Binary |
|---|---|---|---|
A | U+0041 (65) | 1 | 01000001 |
a | U+0061 (97) | 1 | 01100001 |
0 | U+0030 (48) | 1 | 00110000 |
é | U+00E9 (233) | 2 | 11000011 10101001 |
中 | U+4E2D | 3 | 11100100 10111000 10101101 |
🚀 | U+1F680 | 4 | 11110000 10011111 10011010 10000000 |
Where you actually need this
- Bit-level protocol work — I²C, SPI and serial links move bits, and a register value of
0b00000101means specific flags. - File format specifications — magic numbers, flag bytes and length fields are documented as bit patterns.
- Teaching and interviews — why
1 + 1 = 10, why two's complement represents negatives, why a bitmask lets one byte hold eight booleans. - Debugging encoding problems — a stray
11000011 10101001where you expected 8 bits is the signature of a UTF-8 string being read as Latin-1.
Binary output here is grouped per byte, because that is how it is read in practice. An 8-bit row is a byte; a 4-bit row is a nibble, which is what hex digits represent. Splitting a byte across a line boundary is legal but makes the byte structure invisible.
How to use it
- Paste text to see its bit representation, or paste binary to read it back.
- Check the code point shown for each character.
- Note that non-ASCII characters produce more than one byte.
- Space and newline separators are both accepted on input.
Worth knowing
- ASCII covers 128 code points, so seven bits suffice; eight are used for storage.
- Uppercase
Aand lowercaseadiffer by exactly one bit (65 versus 97). - UTF-8 is variable-width: 1 byte for ASCII, up to 4 bytes for emoji.
- Digits 48–57 and letters 65–122 are contiguous ranges, which is why ordering works.
Limitations
- Binary strings are eight times longer than ASCII text and are not compressible by eye.
- Ambiguity is possible if you paste both binary and text into one field — decode expects one form.
- Non-ASCII characters do not fit in a single byte, so a fixed 8-bit assumption fails.
- This is a view of bytes, not of a hardware signal — no framing, parity or timing is represented.