Complete ASCII Table and Text ↔ Code Converter

How the ASCII table and converter work

Here you will find the complete ASCII table, with the 128 codes from 0 to 127: for each one, the value in decimal, hexadecimal, octal and 8-bit binary, the character, the abbreviation of control characters and a description. The search above the table accepts a character, a number such as 65, 0x41 or 01000001, an abbreviation such as CR or a word such as “brace”; the buttons filter by character type.

The converter works in both directions. “Text → codes” turns a sentence into the sequence of its codes, with a character-by-character breakdown. “Codes → text” accepts numbers separated by spaces or commas, recognizes the prefixes 0x (hexadecimal) and 0b (binary) and flags values outside the 0-127 range. Everything happens in the browser: the text is not sent to any server.

What ASCII code is

ASCII (American Standard Code for Information Interchange) is a 7-bit code that assigns a number from 0 to 127 to 128 characters. RFC 20 of 1969, now an Internet Standard, adopted it for network data interchange, taking over the table of the American standard USAS X3.4-1968, with the 7 bits placed in an 8-bit byte whose highest bit is always 0. That is why every code in the “Binary” column starts with a zero.

Codes 0 to 31 and 127 are control characters: they have no graphic symbol and were used to control printing, display and data transmission. Among them are the HT tab (9), the LF line feed (10) and the CR carriage return (13). DEL was used to erase characters on punched tape. From 32 (the space) to 126 (the tilde) there are the 95 printable characters: digits, unaccented letters, punctuation and symbols. The first 128 Unicode code points, from U+0000 to U+007F, contain the same characters in the same order.

How to read the table

RFC 20 arranges the codes in 8 columns and 16 rows: the column corresponds to the three highest bits, the row to the four lowest. “K” is in column 4 and row 11, that is 4 × 16 + 11 = 75, in binary 1001011. This produces useful patterns: uppercase letters run from 65 to 90 and lowercase from 97 to 122, so the same letter always differs by 32; the digits 0 to 9 occupy codes 48 to 57, so the value of a digit is its code minus 48.

Calculation example

Let’s convert “Ciao!” with the “Text → codes” tab. The calculator returns decimal, hexadecimal and binary; the octal value comes from the 0-127 table:

In sequence the word becomes 67 105 97 111 33 in decimal and 43 69 61 6F 21 in hexadecimal; pasting either line into “Codes → text” gives back “Ciao!”. With “Caffè” the last letter is not ASCII: the converter writes 67 97 102 102 U+00E8 and warns that U+00E8 is the Unicode code point of “è”, not an ASCII code.

Characters missing from the Italian keyboard

On the standard Windows Italian layout the tilde and the grave accent have no key, while the at sign, hash sign and square and curly brackets are typed with AltGr. Key combinations and Alt codes:

Hold down Alt, type the number on the numeric keypad and release Alt. According to Microsoft, the row of numbers above the letters does not work, and Num Lock must be turned on if the keyboard requires it. On a laptop without a numeric keypad there is still the Windows “Italian (142)” layout, where the tilde is AltGr + + and the grave accent AltGr + ù.

The leading zero changes the table. Without the zero, for MS-DOS compatibility, Windows looks up the number in the OEM code page; with the zero, in the ANSI code page. For Italian, Windows uses OEM 850 and ANSI 1252, which match ASCII between 32 and 126: Alt+126 and Alt+0126 give the same tilde. Above 127 they do not: “è” is Alt+138 in 850 and Alt+0232 in 1252, and the euro sign is Alt+0128.

Extended ASCII: why there is no single table from 128 to 255

A byte has 256 values and ASCII uses 128 of them. Each code page has filled values 128 to 255 in its own way, so so-called “extended ASCII” is not a single standard:

Microsoft itself warns that ANSI code pages can differ from one computer to another and recommends Unicode. That is why the converter rejects values above 127 and, for non-ASCII characters, shows the Unicode code point, stating that it is one. It does not calculate the bytes of encodings such as UTF-8: it is an informational tool, and for the encoding of a file or a system the documentation of the software you use is authoritative.

Frequently asked questions

What is the ASCII code of the letter A?

Uppercase A has code 65 in decimal, 41 in hexadecimal, 101 in octal and 01000001 in 8-bit binary. Lowercase a has code 97: between the uppercase and lowercase forms of the same letter the difference is always 32, a single bit.

How do you type the tilde on an Italian keyboard?

On the standard Windows Italian layout the tilde has no key. Hold down Alt, type 126 on the numeric keypad with Num Lock on and release Alt: ~ appears. Alt+0126 also works. In the same way, the grave accent is Alt+96.

What is the difference between Alt+nnn and Alt+0nnn?

Without the leading zero Windows looks up the number in the OEM code page (850 for Italian), with the zero in the ANSI code page (Windows-1252 for Italian). From 32 to 126 both tables match ASCII; above 127 they do not: è is Alt+138 or Alt+0232.

Do accented letters like è have an ASCII code?

No. ASCII has 128 characters, from 0 to 127, and no accented letters. è is the Unicode character U+00E8: in the Windows-1252 code page it is byte 232, in 850 byte 138. The value depends on the code page used.

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