ASCII to Decimal Converter Free Online Tool
Convert text to decimal ASCII codes or Unicode code points - strict, byte, UTF-8, or code-point mode. Free, client-side, instant, offline.
Convert text to decimal numbers. Choose code points (one number per character — handles emoji correctly), UTF-8 bytes (multi-byte safe), extended byte (0–255), or strict ASCII (0–127).
How to Use ASCII to Decimal Converter Free Online Tool
- Type or paste text into the input - ASCII, Latin characters, CJK, and emoji are all accepted. The output recomputes within 150 ms of your last keystroke.
- Choose an encoding mode. Code points is the correct default for "one number per visible character" - 😀 is
128512. UTF-8 bytes flattens multi-byte characters (😀 →240 159 152 128). Extended byte and Strict ASCII enforce 0-255 or 0-127 and skip anything outside their range. - Pick a separator: single space for readable output, comma + space for CSV, newline for column output, or JSON array (
[65, 66, 67]) for paste-ready JavaScript/Python literals. - Read the stats line: mode, character count, output count, and the minimum/maximum decimal value. When a strict mode skips characters, the skipped count is shown too.
- Watch for the inline warning. In strict or byte mode, characters outside the range are listed in the red banner so you can adjust either the text or the mode.
- Copy writes the decimals to the clipboard. Download .txt saves a timestamped file named
decimal-<mode>-<iso>.txt. Clear wipes everything. - Press
Ctrl+Enter(⌘+Enteron Mac) to convert and copy in a single shortcut - handy when iterating over different modes for the same input.
Frequently asked questions
What are ASCII decimal values?
Numbers from 0 to 127 that represent each character in the 7-bit ASCII standard – uppercase A is 65, lowercase a is 97, and the space character is 32. These are the codes the browser stores in memory for every character of text.
Is my text secure when converting?
Yes. Conversion runs entirely in your browser – nothing is uploaded, cached, or tracked. After the page loads you can disconnect the network and keep converting indefinitely.
Can I convert long texts or entire documents?
Yes. The tool handles any reasonable length in real time – tens of thousands of characters finish in under 50 ms on a modern laptop. Very long pastes stay smooth because input is debounced by 150 ms.
Which characters have decimal values?
Every character has a numeric code point. Pure ASCII covers 0-127; Latin-1 extends to 255; full Unicode goes up to 0x10FFFF (1 114 111). The mode selector lets you decide which range you want, and the output either restricts or expands accordingly.
Why convert characters to decimal numbers?
For programming (character comparisons, sorting, hashing), debugging protocols or serial dumps, teaching character encoding, and building numeric fixtures for tests. The JSON-array separator is especially handy when you want a copy-paste-ready literal for code.
Does this tool work offline?
Yes. HTML, CSS, and JavaScript are self-contained. Once the page has loaded you can turn off Wi-Fi and keep converting – useful on air-gapped machines.
Is the converter free?
Yes, 100% free with no cap on input length or number of conversions. No sign-up, no premium tier, no watermark.
How do I convert decimal values back to ASCII text?
Use the sibling Decimal to ASCII converter. Round-trip is exact: the output of this tool in code-point mode pastes cleanly back, emoji and all.
What is the difference between code points and UTF-8 bytes?
Code points are one number per visible character (😀 = 128512). UTF-8 bytes are the actual on-the-wire encoding (😀 = 240 159 152 128, four bytes). Pick code points when you want character-level numbers; pick UTF-8 bytes when you want the exact serialised byte stream.
Which browsers support this converter?
Every modern browser: Chrome, Firefox, Safari, Edge, Opera, plus mobile browsers on iOS and Android. The only requirements are JavaScript and a working TextEncoder, both standard since 2016.