Math
ASCII to Binary Converter
Every character you type is stored as one or more bytes.
Enter text to see each character's code point and its bytes in binary, hex, and decimal, or paste binary, hex, or decimal bytes to decode them back to text. Encoding follows UTF-8, so plain ASCII is one byte per character and everything else is shown byte by byte.
Any characters. ASCII letters use one byte each; accented letters, symbols, and emoji use 2-4 bytes in UTF-8.
Try an example
Result
Result
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- Hexadecimal
- —
- Decimal
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- Size
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What the ASCII to binary converter solves
ASCII assigns the numbers 0-127 to English letters, digits, punctuation, and control characters; 'A' is 65, 'a' is 97, '0' is 48. Written in 8 bits, 'A' is 01000001. UTF-8 extends ASCII so that every other character (é, €, 😀) becomes 2 to 4 bytes while ASCII stays unchanged. This converter shows the exact bytes for any text and decodes bytes back.
Handy ASCII values
| Char | Decimal | Hex | Binary |
|---|---|---|---|
| space | 32 | 20 | 00100000 |
| 0 | 48 | 30 | 00110000 |
| 9 | 57 | 39 | 00111001 |
| A | 65 | 41 | 01000001 |
| Z | 90 | 5A | 01011010 |
| a | 97 | 61 | 01100001 |
| z | 122 | 7A | 01111010 |
How to use it
- Choose Text → binary and type or paste the text; the result lists one 8-bit group per byte.
- Or choose Binary → text, pick how the bytes are written (binary, hex, or decimal), and paste them separated by spaces.
- Read the per-character table for the code point (U+0041) and the byte values in every base.
- Use the size line to see how many bytes and bits the text occupies.
How to read the answer
Each 8-bit group is one byte. For ASCII text the groups line up one per character. For characters beyond ASCII the table shows several bytes on one row, so you can see that é is C3 A9 (two bytes) and an emoji is four. Uppercase and lowercase letters differ by exactly one bit (bit 5), which the binary makes visible.
Common mistakes and edge cases
- Dropping leading zeros: 'A' is 01000001, not 1000001. Each byte must be exactly 8 bits when decoding.
- Pasting 7-bit groups from an old ASCII table; add a leading 0 to make each byte 8 bits.
- Decoding a partial multi-byte character gives an error because the bytes are not valid UTF-8.
- Decimal bytes must be 0-255; hex bytes need two digits (0A, not A).
- Line breaks in text are real characters (10 = newline) and appear in the output.
Worked examples
Short word
Hi!
Result
01001000 01101001 00100001
Single letter
A
Result
01000001
Digits
42
Result
00110100 00110010
Non-ASCII character
é (two UTF-8 bytes)
Result
11000011 10101001
Binary to text
01001000 01101001
Result
Hi
Hex to text
48 65 6C 6C 6F
Result
Hello
Decimal to text
72 105
Result
Hi
Wrong group length
1001000 (7 bits)
Result
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Empty text
nothing typed
Result
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Frequently asked questions
What is the letter A in binary?+
'A' is ASCII 65, which is 01000001 in 8-bit binary and 41 in hex. Lowercase 'a' is 97 = 01100001; the two differ only in bit 5.
How do I convert text to binary by hand?+
Look up each character's ASCII code, convert that decimal to binary, and pad to 8 bits. 'H' = 72 = 01001000, 'i' = 105 = 01101001.
Why do some characters take more than one byte?+
ASCII only covers 128 characters. UTF-8 encodes everything else in 2-4 bytes: é is C3 A9, € is E2 82 AC, and most emoji are four bytes.
How do I convert binary back to text?+
Split the bits into 8-bit bytes, convert each to decimal, and look up the character. 01001000 = 72 = 'H'. The converter also accepts hex or decimal bytes.
Is ASCII the same as UTF-8?+
For characters 0-127, yes: every ASCII byte is a valid single-byte UTF-8 character. UTF-8 adds multi-byte sequences for the rest of Unicode.
About this calculator
- Written by
- mathcheck editorial team
- Last reviewed
- September 4, 2026
Method
- Uses the values entered by the user and stable formulas documented on the page.
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Last updated: September 4, 2026