ASCII to UTF-8 Bytes Converter Online Free
Encode ASCII to UTF-8 bytes - hex (x48), decimal, percent (), binary, or octal, with separator and prefix. Free, client-side, instant.
Encode text as its UTF-8 byte sequence — \x48 (C/JS escapes), %48 (URL encoding), decimal, binary, or octal. Multi-byte characters like ä¸ and 😀 expand correctly.
How to Use ASCII to UTF-8 Bytes Converter Online Free
- Paste or type text into the input. ASCII, Latin-1, CJK, and emoji all work - the encoder uses
TextEncoder('utf-8')which handles the full Unicode range. - Pick a byte format. Hex (
\x48) is the classic C/JS string-escape form. Percent-encoded (%48) is URL-encoding style. Decimal for raw byte dumps, binary when you need the bit pattern, octal when you want\012-style escapes. - Pick a separator: space (default), comma, newline, none (continuous dump), or JSON array for paste-ready literals.
- Toggle UPPERCASE for hex output (default on, programming-literal style). Toggle zero-pad for fixed-width tokens (default on - keeps hex/percent/binary/octal columns aligned).
- Override the prefix in the text field if the format's default isn't what you want.
\x(hex),%(percent),0b(binary),0o(octal), empty (decimal) are the defaults - type a new value to replace them. - Check the stats line: character count, byte count, min/max byte value, multi-byte-character count. The multi-byte counter is how you spot non-ASCII input quickly.
- Copy, Download, or press
Ctrl+Enter(⌘+Enteron Mac) to encode and copy in one shortcut. Download saves a timestampedutf8-<format>-<iso>.txtfile.
Frequently asked questions
What is UTF-8?
A variable-width character encoding that uses 1 to 4 bytes per Unicode code point. It is backward-compatible with ASCII (every ASCII character is one UTF-8 byte) and is the dominant encoding on the web today.
What is the difference between ASCII and UTF-8?
ASCII covers 128 characters (0-127) in exactly 7 bits. UTF-8 is a strict superset – it uses one byte for code points 0-127 (identical to ASCII) and two to four bytes for everything above, which means every ASCII file is also a valid UTF-8 file.
What output formats does this tool support?
Five: hex with the x prefix used in C/JS string escapes, percent (%) for URL encoding, raw decimal (0-255), binary (8-bit groups), and octal (3-digit groups).
Is my data secure?
Yes. Encoding runs entirely in your browser – nothing is uploaded, cached, or tracked. After the page loads you can disconnect the network and keep encoding indefinitely.
Does it show multi-byte characters correctly?
Yes. TextEncoder produces the real UTF-8 wire format, so ä¸ expands to three bytes (xE4 xB8 xAD), é to two (xC3 xA9), and 😀 to four (xF0 x9F x98 x80). The stats line’s “multi-byte chars” counter tells you exactly how many characters expanded beyond one byte.
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 number of encodes. No sign-up, no premium tier, no watermark.
How is percent encoding different from hex?
Percent encoding is how URL bytes are represented (%48%69 is “Hi” in a URL). The bytes are exactly the same as hex, just prefixed with % instead of x. Pick this format when you need a paste-ready URL-encoded string.
Does it handle emoji?
Yes. Emoji are 4-byte UTF-8 sequences – 😀 becomes xF0 x9F x98 x80 in hex or %F0 %9F %98 %80 as percent encoding. Perfect for debugging emoji support in databases or APIs.
How do I convert UTF-8 bytes back to text?
Use the sibling UTF-8 to ASCII decoder. It accepts the same formats (hex, percent, decimal, binary, octal) so any output here round-trips back cleanly.