ASCII Table

ASCII (American Standard Code for Information Interchange) is a character encoding standard finalized in the 1960s that assigns a numeric value from 0 to 127 to each letter, digit, punctuation mark, and control signal used in basic English-language computing. It's a strict 7-bit encoding by design (2^7 = 128 possible values), which was a deliberate constraint of the era's hardware — computers commonly used 7-bit or 8-bit bytes, and reserving the 8th bit for parity checking or other purposes was common practice, so the original standard simply never defined values 128-255.

Extended ASCII isn't a single standard — it's an umbrella term for any of dozens of different, mutually incompatible 8-bit character sets that various vendors and regions created to make use of the unused 128-255 range once 8-bit bytes became universal, each assigning different characters (accented Latin letters, box-drawing characters, currency symbols, or entirely different scripts) to the same numeric codes. This table shows the ISO-8859-1 (Latin-1) mapping specifically, since it's the most widely recognized and historically influential version — it's also directly what JavaScript's own String.fromCharCode() function returns for values 128-255, and it forms the basis of the first 256 code points of Unicode itself.

These are control characters — they were never meant to be printed or displayed as visible glyphs, but rather interpreted as instructions by early teletypes, terminals, and later software: signals like 'move to a new line' (Line Feed, 10), 'ring the terminal bell' (BEL, 7), 'end of transmission' (EOT, 4), or 'delete the previous character' (Backspace, 8). Modern software has largely repurposed a handful of these for specific technical roles — Tab (9), Line Feed (10), and Carriage Return (13) remain in constant everyday use for text formatting, while most of the rest (like SOH, ENQ, or the various Device Control codes) are relics of 1960s-70s hardware protocols rarely seen directly today.

This is a genuinely direct, non-coincidental relationship: holding Ctrl and pressing a letter key clears the upper three bits of that letter's ASCII code, which for uppercase A-Z (decimal 65-90) produces exactly the control codes 1-26 — Ctrl+A produces code 1 (SOH), Ctrl+C produces code 3 (ETX, which is why it's used as the universal 'interrupt/break' signal in terminals), Ctrl+I produces code 9 (which is identical to the Tab character), and Ctrl+M produces code 13 (identical to Carriage Return, which is why Ctrl+M and Enter are functionally the same keystroke in many terminal programs). This tool's Keyboard Shortcut Reference table lays out that full mapping.

The underlying value never changes — only the base used to write it down does — and different contexts in programming conventionally favor different bases: decimal is the everyday human-readable form, hexadecimal is the standard way character codes appear in Unicode documentation, URL-encoding (%XX), and most programming language escape sequences (\xNN), octal historically appeared in Unix file permissions and some older escape sequence conventions (\NNN), and binary is the closest representation to how the value is actually stored in memory, useful when reasoning about bitwise operations or hardware-level behavior.

ASCII didn't disappear — it was deliberately preserved as the exact first 128 code points of Unicode, and by extension, is exactly what UTF-8 encodes as single, unmodified bytes for those same 128 characters, which is precisely why UTF-8 remains fully backward-compatible with plain ASCII text. Developers still reach for ASCII tables constantly: debugging an unexpected control character hidden in a file (like a stray Carriage Return causing line-ending issues), writing a regular expression or escape sequence that references a specific code point, working with legacy systems or binary protocols, or simply double-checking the exact numeric value of a punctuation character for a hashing, encoding, or validation task.

Clicking a control character's row copies its actual character value (like the real Tab, newline, or Escape byte) to your clipboard exactly as requested — but because these characters have no visible glyph by design, pasting one into most text fields will appear to insert nothing visible, or may trigger unexpected behavior (a real Tab character moving focus, a real newline breaking a line) rather than displaying a symbol. If you specifically want to copy the readable representation instead, copy the Decimal, Hex, or Name column value for that row rather than the Character column.

Yes, meaningfully — Unicode defines well over 149,000 characters across virtually every writing system in current and historical use, of which ASCII (0-127) and Latin-1 Extended (128-255, shown here) together represent only the very first 256 code points. A full Unicode reference table would be an enormously larger undertaking covering emoji, CJK ideographs, and dozens of other scripts; this tool intentionally stays focused on the specific, foundational 0-255 range that's still directly relevant to everyday programming, terminal work, and legacy system interoperability.