Extended ASCII Lookup

Read a byte in four number systems

This reference filters a fixed table of values from 0 through 255. Each row shows the decimal value, hexadecimal value with a 0x prefix, octal value, eight-bit binary form, character when printable, and a short name for spaces or controls. For example, decimal 169 is hexadecimal 0xA9, octal 251, and binary 10101001; the character shown for that row is ©.

What this table means by “extended”

The 0–127 range is the standard ASCII range. This table labels 0–31 and 127 as control entries, shows 32 as SPACE, and displays the printable characters in between. In the upper range, 128–159 are labeled with C1 control names, while 160–255 display Latin-1 characters. Unicode documents this division as C1 controls followed by the Latin-1 Supplement. “Extended ASCII” is often used loosely for several different eight-bit mappings, so the label alone does not identify how a file or device interprets every byte.

The distinction matters in web text: the WHATWG Encoding Standard maps labels such as “latin1” and “iso-8859-1” to Windows-1252 for web compatibility. Windows-1252 assigns printable symbols to many values shown here as C1 controls. Use the table as the specific C1-and-Latin-1 reference described above, and identify the actual encoding before interpreting bytes from another source. References checked September 29, 2026.

Filter the rows you need

1. Enter a character, decimal value, hexadecimal digits, octal value, binary digits, or a control name in the keyword field. Search matches within the displayed row fields.

2. Choose All (0–255), Standard ASCII (0–127), or Extended Range (128–255). The range choice and keyword filter work together.

3. Read across the matching row to compare its decimal, hexadecimal, octal, and binary forms. Hex values in the results include the 0x prefix; when filtering by hex, enter the digits without that prefix, such as A9.

4. For blank-looking entries such as SPACE or TAB, search by name and use the Note column. Copy a displayed character or control name with its row's copy control.

Lookup questions

Confirm the encoding before interpreting data

There is no single universal “extended ASCII” mapping for bytes 128–255. This reference uses C1 control names for 128–159 and Latin-1 characters for 160–255. A Windows-1252 file, a different code page, or a protocol-specific byte stream may assign different meanings. A byte value by itself cannot establish which mapping applies; check the file format, system setting, or protocol specification before using the displayed character to diagnose or transform data.