Hex to Text Converter

What hexadecimal actually is

Hexadecimal is a base-16 positional number system. Where decimal has ten digits (0–9) and binary has two (0 and 1), hex has sixteen: 0 1 2 3 4 5 6 7 8 9 A B C D E F. The letters A to F stand for the decimal values 10 to 15. Each hex digit therefore encodes exactly four bits, which is why a single byte — eight bits — is always written as exactly two hex digits, from 00 to FF.

That four-bits-per-digit relationship is the whole reason hexadecimal became the standard notation for raw data. Writing the byte 11010110 takes eight characters and is easy to miscount; writing it as D6 takes two and can be read at a glance. Converting between hex and binary requires no arithmetic at all, just a lookup of sixteen four-bit patterns, which you can find in our binary conversion chart.

Hex digit values

How hex-to-text conversion works

Text is not stored as letters. It is stored as numbers, and those numbers are stored as bytes. Converting hex to text is therefore a three-step pipeline, and the middle step is where almost every bug lives.

1. Parse hex into bytes. Every pair of hex digits becomes one byte with a value between 0 and 255. 48 becomes 72, 65 becomes 101, and so on. Separators, 0x prefixes and line breaks are ignored.
2. Interpret the bytes with an encoding. The byte 72 means the letter H in ASCII, in UTF-8 and in Latin-1, because all three agree on the first 128 values. Above 127 they diverge sharply. The byte sequence C3 A9 is the single character é in UTF-8 but the two characters é in Latin-1.
3. Render the resulting characters. Code points are mapped to glyphs by the font. A missing glyph shows as a box, which is a font problem, not an encoding problem.

Choosing the right encoding

The tool offers three interpretations of the same bytes, and picking the wrong one is the single most common cause of garbled output.

If output looks like é, ’ or a run of question marks, the bytes are almost certainly UTF-8 being read as Latin-1. Switch encoding rather than editing the data. Our character encoding guide works through the whole family of failure modes.

Where hex dumps show up in real work

• Network debugging. Packet captures in Wireshark, tcpdump and curl’s --trace output are hex dumps. Decoding a payload by hand is often the fastest way to confirm what a client actually sent.
• File format forensics. Every format starts with a magic number: 25 50 44 46 is %PDF, 89 50 4E 47 is a PNG, 50 4B 03 04 is a ZIP archive (and therefore also a .docx or .xlsx).
• Embedded systems. Serial protocols, EEPROM dumps and firmware images are read as hex. Converting a region back to text quickly reveals version strings and configuration blobs.
• Security analysis. Shellcode, obfuscated payloads and malware configuration are routinely hex-encoded to survive transport through text channels, much like Base64.
• Databases. Binary columns are displayed as hex by MySQL, PostgreSQL (\x notation) and SQL Server, so decoding hex is a daily task when inspecting BLOB data.

Doing it in code

JavaScript

// hex string -> text (UTF-8)
const hexToText = hex =>
  new TextDecoder().decode(
    Uint8Array.from(hex.replace(/[^0-9a-f]/gi, '').match(/../g), b =>
      parseInt(b, 16))
  );

// text -> hex string
const textToHex = str =>
  [...new TextEncoder().encode(str)]
    .map(b => b.toString(16).padStart(2, '0'))
    .join(' ');

Python

bytes.fromhex('48656c6c6f').decode('utf-8')   # 'Hello'
'Hello'.encode('utf-8').hex(' ')                  # '48 65 6c 6c 6f'

Command line

echo -n 'Hello' | xxd -p        # 48656c6c6f
echo '48656c6c6f' | xxd -r -p   # Hello

Frequently Asked Questions