The Alphabet in Binary
Every letter of the English alphabet as an 8-bit binary byte (ASCII/UTF-8), with matching decimal and hex codes. To convert whole words or sentences, use the binary translator.
How letters become binary
Computers store text as numbers. ASCII assigns every character a code - uppercase A is 65, lowercase a is 97 - and that code is written as one 8-bit binary byte. Uppercase and lowercase pairs differ by exactly one bit (value 32, binary 00100000), which is why A is 01000001 and a is 01100001.
Uppercase Letters A-Z
| Character | Binary | Decimal | Hex |
|---|---|---|---|
| A | 01000001 | 65 | 0x41 |
| B | 01000010 | 66 | 0x42 |
| C | 01000011 | 67 | 0x43 |
| D | 01000100 | 68 | 0x44 |
| E | 01000101 | 69 | 0x45 |
| F | 01000110 | 70 | 0x46 |
| G | 01000111 | 71 | 0x47 |
| H | 01001000 | 72 | 0x48 |
| I | 01001001 | 73 | 0x49 |
| J | 01001010 | 74 | 0x4A |
| K | 01001011 | 75 | 0x4B |
| L | 01001100 | 76 | 0x4C |
| M | 01001101 | 77 | 0x4D |
| N | 01001110 | 78 | 0x4E |
| O | 01001111 | 79 | 0x4F |
| P | 01010000 | 80 | 0x50 |
| Q | 01010001 | 81 | 0x51 |
| R | 01010010 | 82 | 0x52 |
| S | 01010011 | 83 | 0x53 |
| T | 01010100 | 84 | 0x54 |
| U | 01010101 | 85 | 0x55 |
| V | 01010110 | 86 | 0x56 |
| W | 01010111 | 87 | 0x57 |
| X | 01011000 | 88 | 0x58 |
| Y | 01011001 | 89 | 0x59 |
| Z | 01011010 | 90 | 0x5A |
Lowercase Letters a-z
| Character | Binary | Decimal | Hex |
|---|---|---|---|
| a | 01100001 | 97 | 0x61 |
| b | 01100010 | 98 | 0x62 |
| c | 01100011 | 99 | 0x63 |
| d | 01100100 | 100 | 0x64 |
| e | 01100101 | 101 | 0x65 |
| f | 01100110 | 102 | 0x66 |
| g | 01100111 | 103 | 0x67 |
| h | 01101000 | 104 | 0x68 |
| i | 01101001 | 105 | 0x69 |
| j | 01101010 | 106 | 0x6A |
| k | 01101011 | 107 | 0x6B |
| l | 01101100 | 108 | 0x6C |
| m | 01101101 | 109 | 0x6D |
| n | 01101110 | 110 | 0x6E |
| o | 01101111 | 111 | 0x6F |
| p | 01110000 | 112 | 0x70 |
| q | 01110001 | 113 | 0x71 |
| r | 01110010 | 114 | 0x72 |
| s | 01110011 | 115 | 0x73 |
| t | 01110100 | 116 | 0x74 |
| u | 01110101 | 117 | 0x75 |
| v | 01110110 | 118 | 0x76 |
| w | 01110111 | 119 | 0x77 |
| x | 01111000 | 120 | 0x78 |
| y | 01111001 | 121 | 0x79 |
| z | 01111010 | 122 | 0x7A |
Digits 0-9
| Character | Binary | Decimal | Hex |
|---|---|---|---|
| 0 | 00110000 | 48 | 0x30 |
| 1 | 00110001 | 49 | 0x31 |
| 2 | 00110010 | 50 | 0x32 |
| 3 | 00110011 | 51 | 0x33 |
| 4 | 00110100 | 52 | 0x34 |
| 5 | 00110101 | 53 | 0x35 |
| 6 | 00110110 | 54 | 0x36 |
| 7 | 00110111 | 55 | 0x37 |
| 8 | 00111000 | 56 | 0x38 |
| 9 | 00111001 | 57 | 0x39 |
Code Examples
// Letter to binary
'A'.charCodeAt(0).toString(2).padStart(8, '0'); // "01000001"
// Whole word to binary
[...'hi'].map(c =>
c.charCodeAt(0).toString(2).padStart(8, '0')
).join(' '); // "01101000 01101001"Frequently Asked Questions
What is the letter A in binary?
Uppercase A is 01000001 in 8-bit binary (decimal 65, hex 0x41). Lowercase a is 01100001 (decimal 97, hex 0x61).
Why are uppercase and lowercase letters 32 apart?
ASCII places each lowercase letter exactly 32 positions after its uppercase pair, so they differ by a single bit (00100000, or 0x20). Flipping that one bit switches the case of any letter.
How do I write a word in binary?
Look up each letter's 8-bit code and write them in order. For example, 'hi' is 01101000 01101001. Our binary translator does this instantly for whole sentences.
Is this table ASCII or UTF-8?
Both. For the English alphabet, digits, and common punctuation, UTF-8 encodes each character as the identical single byte defined by ASCII, so the same table applies.
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