ASCII to Octal Converter Online Free Tool
Convert ASCII to Octal (base 8) - code points or UTF-8 bytes, with separators, padding, and prefix. Free, client-side, instant, offline.
Convert text to base-8 numbers — choose code points (one token per character, emoji-safe) or UTF-8 bytes, with separator, padding, and prefix controls.
How to Use ASCII to Octal Converter Online Free Tool
- Type or paste text into the input. ASCII, Latin characters, CJK, and emoji are all accepted. The output recomputes within 150 ms of every keystroke.
- Pick an encoding mode. Code points (default) emits one token per visible character. UTF-8 bytes emits each byte of the UTF-8 encoding -
ä¸becomes three tokens (344 270 255), matching the on-disk byte sequence. Extended byte and Strict ASCII enforce 0-255 or 0-127 ranges. - Pick a separator: space (default), comma + space, newline, none (continuous dump), or JSON array (paste-ready literal).
- Tick "Zero-pad to 3 digits" to force
012over12. Default on - every byte value fits in exactly 3 octal digits, which keeps columns aligned and makes Unix-permission-style dumps readable. Code points above 255 aren't padded (they're naturally longer). - Add a per-token prefix like
0o(JavaScript/Python octal literal),\0(C octal escape), or leave blank for bare numbers. - Check the stats line: mode, char count, token count, min/max value (in octal subscript), and skipped count.
- Copy, Download, or press
Ctrl+Enter(⌘+Enteron Mac) to encode and copy in one shortcut - especially handy when working out Unix file permissions.
Frequently asked questions
What is octal?
A base-8 number system using the digits 0-7. Each octal digit represents exactly 3 bits, so one byte (8 bits) needs three octal digits to express – which is why octal used to be popular for dumping bytes on hardware where word sizes were multiples of 3.
Why convert text to octal?
Unix file-permission strings (chmod 755), legacy C and PDP-11 code dumps, octal escape sequences in string literals ( , 12), teaching positional number systems, or debugging embedded protocols that speak in octal.
What is the output format?
Depends on your picks. Default is space-separated 3-digit zero-padded octal (110 145 154 154 157), but you can switch to comma, newline, continuous dump, or JSON array. Prefixes like 0o or attach to each token when you set one.
Is my data secure?
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.
Why are tokens padded with leading zeros?
So every byte lines up in a 3-column grid, which makes hex-dump-style output easier to read. Untick the pad toggle to get the natural length (12 instead of 012).
Does it work offline?
Yes. HTML, CSS, and JavaScript are self-contained. Once the page has loaded, you can turn off Wi-Fi and keep encoding – useful on air-gapped machines.
Is it free?
Yes, 100% free with no cap on input length or conversions. No sign-up, no premium tier, no watermark.
How does Unix chmod relate to this?
Unix file-permission triplets (owner, group, other) each fit in 3 bits – read = 4, write = 2, execute = 1. Sum them for each triplet and you get an octal digit: rwxr-xr-x = 7-5-5 = 755. The tool isn’t a chmod calculator, but the octal numbers you produce here are the same kind of 3-bit-packed value.
Does it handle emoji and non-Latin text?
Yes. Iteration uses Array.from + codePointAt, so 😀 emits a single octal token (373000) rather than two surrogate halves. Switch to UTF-8 mode to see the actual four-byte sequence instead.
How do I convert octal back to text?
Use the sibling Octal to ASCII converter. It accepts the same mode selector, so any output here round-trips cleanly.