Base64 vs Hex — Key Differences

4 min readUpdated January 2025Developer Tools

Both Base64 and hex are ways to represent binary data as text — but they have very different characteristics. Here's when to use each and why it matters.

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Quick comparison

Feature	Base64	Hex (Base16)
Characters used	A-Z, a-z, 0-9, +, / (64 chars)	0-9, a-f (16 chars)
Size vs binary	+33% larger	+100% larger (2x)
Readability	Compact but opaque	Longer but byte-level readable
URL safe?	No (use Base64URL variant)	Yes
Common use	JWTs, data URLs, email	Hashes, checksums, colour codes

When to use Base64

Base64 is the right choice when you need to embed binary data in text-based formats — especially when file size matters:

JWTs — header and payload are Base64URL encoded
Data URLs — data:image/png;base64,... for inline images
Email attachments — MIME encoding
API authentication — HTTP Basic Auth is Base64-encoded
Embedding files in JSON — smaller than hex for the same data

When to use hex

Hex is better when human readability at the byte level matters, or when debugging binary data:

Cryptographic hashes — SHA-256, MD5 output is shown as hex (e.g. a3f5...)
Checksums — file integrity verification
Colour codes — CSS hex colours (#ff6600)
Memory addresses — debuggers and hex editors show addresses in hex
Binary protocol debugging — each hex pair = exactly one byte

Size comparison example

Same data, three encodings

Binary data: [0x48, 0x65, 0x6C, 0x6C, 0x6F]  (5 bytes = "Hello")

Hex:    48656c6c6f          (10 chars — 2x the binary size)
Base64: SGVsbG8=            (8 chars — 1.6x the binary size)
Text:   Hello               (5 chars — original)

For a 1 MB binary file: hex produces 2 MB of text, Base64 produces 1.33 MB. Base64 is significantly more compact when transmitting or storing binary data as text.

Converting between formats in JavaScript

Hex to Base64

function hexToBase64(hex) {
  const bytes = hex.match(/.{1,2}/g).map(b => parseInt(b, 16));
  return btoa(String.fromCharCode(...bytes));
}

hexToBase64('48656c6c6f'); // "SGVsbG8="

Base64 to Hex

function base64ToHex(b64) {
  return [...atob(b64)]
    .map(c => c.charCodeAt(0).toString(16).padStart(2, '0'))
    .join('');
}

base64ToHex('SGVsbG8='); // "48656c6c6f"

Frequently asked questions

Is Base64 more secure than hex?

Neither is secure — both are encodings, not encryption. Anyone can decode both without a key. The choice between them is purely about format and size, not security.

Why do SHA-256 hashes look like hex strings?

Cryptographic hash functions output raw bytes. Hex is the conventional way to display hashes because each hex character directly represents 4 bits — making it easy to see exactly how many bytes the hash is (SHA-256 = 32 bytes = 64 hex chars).

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