Hex Converter

About Hex converter

Converts text into hexadecimal bytes and back again, working on the UTF-8 bytes of the text, so accented letters, non-Latin scripts and emoji come out as the byte sequences other systems use. On the encoding side you can choose upper or lower case, an optional 0x prefix and whether bytes are separated by spaces, which makes the output easy to paste into source code or compare with a hex dump.

How to use it

1. Stay on the Text to Hex tab and type your text into the Text to Convert box.
2. In the Options card, set the switches: Uppercase hex values, Add "0x" prefix and Add spaces between values.
3. Press Convert to Hex and copy the Hex Output.
4. To go the other way, open Hex to Text, paste the values and press Convert to Text.

Plain text, then an accented letter and an emoji

Hello, é and 😀

Hello with the defaults (prefix and spaces on): 0x48 0x65 0x6c 0x6c 0x6f
With the prefix and spaces off: 48656c6c6f
é is 0xc3 0xa9, and 😀 is 0xf0 0x9f 0x98 0x80

When to use it

• Writing a string as a byte array in C, Arduino or embedded firmware source.
• Comparing a short message with what a debugger or packet capture displays.
• Decoding a hex snippet from a forum post or an old configuration file.
• Looking up the code of a character without opening a character table.

Questions about Hex converter

Do the hex values need spaces or a 0x prefix when decoding?

Neither. Spaces, commas, line breaks and every 0x marker are treated as separators, and the rest is read two digits at a time, so 48 65 6c 6c 6f, 0x48 0x65 and 48656c6c6f all work.

What if I enter an odd number of digits?

You get an error that quotes the offending group and its digit count, such as 486 having three digits, because every byte needs exactly two. Add the missing leading zero or recount your pairs and try again.

Do euro signs and emoji survive a round trip?

Yes. The euro sign becomes the three bytes e2 82 ac and an emoji becomes four bytes, and decoding reads those bytes back as UTF-8, so the original text returns. Decoding a UTF-16 style value such as 20ac fails, because those bytes are not valid UTF-8.

Does it produce UTF-8 bytes?

Yes, always. Plain English text gives one byte per character, while an accented letter gives two bytes, most other scripts three, and an emoji four, exactly as a UTF-8 file would hold them.

What input is rejected when decoding?

Anything other than 0-9 and a-f in either case, once separators and 0x markers are set aside, is rejected, and the message names the first bad character. Bytes that do not form valid UTF-8 text, such as ff fe, are reported too.

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