Skip to content
Lizely

ASCII Converter

Convert standard 7-bit ASCII text to decimal codes or decode decimal codes back to exact ASCII characters locally.

Privacy: your files never leave your device. All processing happens locally in your browser.

How to use

  1. 1.Choose whether to encode ASCII text or decode decimal ASCII codes.
  2. 2.Enter text or decimal values from 0 to 127 separated by spaces, commas, or line breaks.
  3. 3.Select Convert ASCII, review invisible control-character implications, and copy the result if needed.

About ASCII Converter

ASCII Converter performs strict two-way conversion between standard 7-bit ASCII characters and decimal code values. Choose text-to-codes to turn each character into a space-separated decimal integer, or choose codes-to-text to decode integers separated by spaces, commas, or line breaks. Processing stays in the current browser tab.

The accepted range is exactly decimal 0 through 127. This includes control characters, punctuation, digits, uppercase and lowercase Latin letters, and DEL. Eight independent standard fixtures pin the lower boundary, TAB, LF, Space, digit zero, uppercase A, lowercase a, and the upper boundary. Assignments follow IETF RFC 20 and are cross-checked against Unicode's C0 Controls and Basic Latin chart.

Encoding rejects the first character outside 7-bit ASCII and reports its position. Decoding requires plain decimal integers and rejects signs, fractions, hexadecimal prefixes, empty tokens, and values above 127. The tool does not silently reinterpret values 128–255 because the phrase extended ASCII can refer to incompatible code pages such as Windows-1252 or ISO-8859-1.

Control codes may be invisible in the output textarea. For example, decimal 9 is a tab, 10 is line feed, 13 is carriage return, 0 is NUL, and 127 is DEL. Copying control characters into another application can trigger application-specific behavior, so use the decimal output or a byte-aware editor when visibility matters.

This tool differs from the ASCII Table, which is a searchable one-row reference, and from Text to Hex or Binary converters, which encode UTF-8 bytes in other bases. ASCII Converter handles a complete text sequence as decimal 7-bit values and fails closed when the input is not ASCII.

The input limit is 100,000 UTF-16 code units, with a 50,000-code bound on decoding. For Unicode code points, UTF-8 bytes, legacy code pages, binary files, or locale-specific character conversion, use a converter that explicitly names the required encoding rather than treating it as ASCII.

Methodology & sources

Enforce a bounded input, encode each UTF-16 code unit only when its value is 0 through 127, serialize codes as decimal integers, tokenize decoded input on commas or whitespace, require unsigned one-to-three-digit decimal tokens, reject values outside 0 through 127 and excessive token counts, reconstruct exact ASCII code units, and expose no extended-code-page fallback.

Frequently asked questions

Does this support values 128 through 255?
No. Standard ASCII is 7-bit and ends at 127; higher values require a named character encoding.
Why is part of decoded output invisible?
Codes 0–31 and 127 are controls, so tabs and line breaks may act visually while other controls show no glyph.
Can it convert Unicode or emoji?
No. Non-ASCII characters are rejected instead of being silently encoded as UTF-8 or a legacy code page.
Is the text uploaded?
No. Encoding, decoding, and validation run locally in the browser.

Related tools

Encoding & Crypto guides

View all