Convert Decimal to ASCII

Strict ASCII is 0-127 (7 bits): letters, digits, punctuation, and control codes. “Extended ASCII” is not a single standard – the name usually refers to one of several 8-bit encodings (Latin-1, Windows-1252, etc.) that fill 128-255 with additional characters. This tool’s Extended mode decodes bytes 128-255 as Latin-1 (ISO 8859-1) code points.

Unicode mode accepts any value up to 1,114,111 (the top of the Unicode code-point range, U+10FFFF). So decimal 128512 converts to 😀 (U+1F600). Supplementary-plane code points are handled via String.fromCodePoint. Stats flag how many are non-BMP (>0xFFFF).

Because 10 is the ASCII/Unicode code for line-feed (LF), a control character. In raw mode the tool inserts the literal LF, so your output has a real newline in it. Switch to show as labels to render it as [LF] – useful when you need to SEE where invisible bytes land.

Values 0-31 are control codes named by ASCII: NUL, SOH, STX, ETX, EOT, ENQ, ACK, BEL, BS, TAB, LF, VT, FF, CR, SO, SI, DLE, DC1-DC4, NAK, SYN, ETB, CAN, EM, SUB, ESC, FS, GS, RS, US. Value 127 is DEL. Label mode brackets them like [BS] or [DEL] so they become visible.

It rejects them with specific reasons in the breakdown. -1 is flagged as “negative value”; abc as “not a decimal number”; 300 under strict ASCII as “out of ASCII range 0-127”. Stats show the count of invalid tokens, so nothing goes missing silently.

Yes – any combination of whitespace, commas, semicolons, and pipes is treated as a separator. So 72, 101; 108 | 108n111 parses as five tokens and decodes to Hello.

Because you have decimal-encoded data. Common sources: C/Python ord() output, Wireshark packet bytes displayed as decimals, telnet negotiation codes (IAC = 255), old BASIC CHR$ examples. If your source is hex (48 65 6C 6C 6F), use the hex-to-ASCII variant instead – this tool would try to parse 48 as decimal 48 = '0', not 'H'.

Up to about 10,000 decimal tokens in under 50ms on a typical laptop. Beyond that, the browser’s textarea rendering becomes the bottleneck, not the parsing. The logic itself scales linearly.

Use an ASCII-to-decimal encoder tool. For a single round-trip with no info loss, keep the same range mode: strict-to-strict, extended-to-extended, Unicode-to-Unicode. Our ASCII-to-decimal converter handles all three.

Yes. Everything computes in your browser with plain arithmetic and String.fromCharCode / String.fromCodePoint. No upload, no tracking, no account. Load the page once and it works offline indefinitely.