What an ASCII Binary Table Shows
An ASCII binary table maps characters to numeric codes and binary byte values. ASCII assigns values from 0 to 127 to English letters, digits, punctuation, and control characters. Because a byte has eight bits, ASCII values are usually displayed as 8-bit binary groups.
For example, uppercase A is decimal 65, hexadecimal 41, and binary 01000001. Lowercase a is decimal 97, hexadecimal 61, and binary 01100001.
Common Letters
| Character | Decimal | Hex | Binary |
|---|---|---|---|
| A | 65 | 41 | 01000001 |
| B | 66 | 42 | 01000010 |
| C | 67 | 43 | 01000011 |
| X | 88 | 58 | 01011000 |
| Y | 89 | 59 | 01011001 |
| Z | 90 | 5A | 01011010 |
| a | 97 | 61 | 01100001 |
| b | 98 | 62 | 01100010 |
| c | 99 | 63 | 01100011 |
| x | 120 | 78 | 01111000 |
| y | 121 | 79 | 01111001 |
| z | 122 | 7A | 01111010 |
The pattern is useful: uppercase letters are grouped together, lowercase letters are grouped together, and the difference between uppercase and lowercase English letters is 32 in decimal.
Digits in Binary
The digit characters are not the same as the numeric values they display. The character 0 has ASCII value 48, not decimal zero.
| Character | Decimal | Binary |
|---|---|---|
| 0 | 48 | 00110000 |
| 1 | 49 | 00110001 |
| 2 | 50 | 00110010 |
| 3 | 51 | 00110011 |
| 4 | 52 | 00110100 |
| 5 | 53 | 00110101 |
| 6 | 54 | 00110110 |
| 7 | 55 | 00110111 |
| 8 | 56 | 00111000 |
| 9 | 57 | 00111001 |
This distinction matters when decoding binary. 00110001 represents the character 1; the numeric value one would be 00000001 as a raw byte.
Spaces and Punctuation
| Character | Decimal | Binary |
|---|---|---|
| space | 32 | 00100000 |
| ! | 33 | 00100001 |
| " | 34 | 00100010 |
| # | 35 | 00100011 |
| . | 46 | 00101110 |
| / | 47 | 00101111 |
| : | 58 | 00111010 |
| ? | 63 | 00111111 |
| @ | 64 | 01000000 |
Spaces are easy to miss because they are invisible in text. In binary output, each space appears as 00100000.
ASCII vs UTF-8
UTF-8 is backward compatible with ASCII for values 0 to 127. That means the binary representation of English letters, digits, and basic punctuation is the same in ASCII and UTF-8. Characters outside ASCII, such as é, ñ, €, or emoji, use multiple UTF-8 bytes.
How to Use the Table
To convert text manually, look up each character, write its 8-bit binary value, and join the bytes with spaces. The word Hi becomes:
H = 01001000
i = 01101001
Hi = 01001000 01101001To decode binary, split the binary string into 8-bit groups, convert each group to decimal, then map the decimal value back to a character.
Frequently Asked Questions
Is ASCII still used?
Yes. ASCII remains the foundation for many protocols, file formats, and programming concepts. Modern text usually uses UTF-8, but UTF-8 preserves ASCII values for the first 128 code points.
Why are ASCII bytes shown with leading zeros?
Leading zeros make each value a full 8-bit byte. For example, A could be written as 1000001, but 01000001 makes byte boundaries clear.
Can ASCII represent emoji?
No. Emoji require Unicode and are commonly encoded as multiple UTF-8 bytes.