How to use it
- Type a decimal code such as 65, a hexadecimal code such as 0x41, a binary code such as 0b1000001, a character such as A, or a word such as bell in the Search box.
- Choose Control codes or Printable characters in the Show list to narrow the table, or keep All codes to see all 128.
- Read across a row: the decimal, hexadecimal, octal and binary values are the same code, and the character, or the abbreviation and name, says what it is.
What ASCII is and how the table is built
ASCII, the American Standard Code for Information Interchange, gives a number from 0 to 127 to each of 128 characters. RFC 20 (1969) sets out its code table and the names of its codes. The codes 0 to 31 and 127 are control codes: they were written for teletypes and terminals, such as line feed (LF, 10) or escape (ESC, 27), and most of them have no printed form. The codes 32 to 126 are printable: the space, the letters, the digits and the signs you can type.
Unicode's Basic Latin block gives the same 128 code points the same numbers, so U+0041 is the letter A, with code 65 in every number base the table shows.
The four number bases
Decimal, base 10, is the everyday number. Hexadecimal, base 16, uses the digits 0 to 9 and the letters A to F, so 65 is 41 (4 × 16 + 1). Octal, base 8, uses the digits 0 to 7, so 65 is 101 (1 × 64 + 0 × 8 + 1). Binary, base 2, uses only 0 and 1, so 65 is 1000001 (64 + 1). Programmers usually write a hexadecimal code with a 0x prefix, as in 0x41.
The table pads the binary values to seven digits and the octal values to three, so every row lines up.
65 = 41 in hexadecimal = 101 in octal = 1000001 in binaryWorked example: the letter A and the escape code
Type A in the Search box. The table shows one row, for code 65, with the hexadecimal value 41, the octal value 101 and the binary value 1000001.
Type esc. The row for code 27 shows the abbreviation ESC and the name Escape, with the hexadecimal value 1B, the octal value 033 and the binary value 0011011.
Frequently asked questions
Why does the table stop at 127 and not 255?
ASCII uses seven bits, so its codes run from 0 to 127. Extended sets such as ISO 8859-9, used for Turkish, add accented letters such as ş and ğ at codes above 127. This table shows only the 128 ASCII codes.
Which control codes still matter?
Most control codes have lost their first purpose, but some still matter. LF (10) ends a line in Unix and on the web, CR (13) followed by LF ends a line in Windows text files, HT (9) is the tab, and ESC (27) starts the colour and cursor codes of a terminal.
Is the character 0 the same as the number 0?
No. The character 0 has code 48, which is 30 in hexadecimal, while code 0 is the NUL control character. A digit typed on a keyboard is stored as its code, which is 48 to 57 for 0 to 9.
Why are capital and small letters 32 apart?
A is code 65 (41 in hexadecimal) and a is code 97 (61 in hexadecimal), so the difference is 32. Setting that one bit changes the case of a letter, which is why simple case conversion is fast.
Are the ASCII codes the same in UTF-8 files?
Yes. In UTF-8, the encoding of the web, every ASCII character is stored in one byte with the same value, so the codes in this table are the codes a text file holds. Some older encodings, such as the EBCDIC codes of some mainframes, use different numbers.
Sources
- RFC 20: ASCII format for Network Interchange (1969), code table and names
- Unicode Character Database, UnicodeData.txt (names of the letters and digits)
Figures and text last checked on Wednesday, November 11, 2026.