Base64 vs Hexadecimal Encoding

Base64 and hexadecimal are both methods for representing binary data as printable text, but they differ significantly in efficiency, readability, and typical use cases.

Size comparison for encoding 1 byte:

• Original: 1 byte (8 bits)
• Hexadecimal: 2 characters (each hex digit represents 4 bits)
• Base64: approximately 1.33 characters (each Base64 character represents 6 bits)

For a concrete example, encoding 100 bytes:

• Hex: 200 characters (2x expansion)
• Base64: 136 characters (1.33x expansion, with padding)

This means Base64 is about 33% more compact than hex for the same data. For large payloads like embedded images or file attachments, this difference is significant.

Readability: Hex is more human-readable for short values. A hex string like 48656C6C6F can be mentally decoded character by character (0x48 = H, 0x65 = e, etc.). Base64 strings like SGVsbG8= are opaque unless you decode them.

Hex is also easier to work with at the byte level. Each pair of hex characters is exactly one byte, making it simple to inspect individual bytes, compare hashes, or identify file signatures (magic bytes).

When to use hex:

• Displaying hash values (MD5, SHA-256) -- the convention is hexadecimal.
• Debug output showing raw bytes, memory addresses, or packet contents.
• Color codes in CSS (#FF5733).
• Short identifiers where readability matters more than compactness.

When to use Base64:

• Transmitting binary data in text-based protocols (JSON, XML, email).
• Embedding files in HTML/CSS (data URIs).
• API authentication tokens and credentials.
• Any context where minimizing the encoded size matters.

Encoding comparison in JavaScript:

const bytes = new Uint8Array([72, 101, 108, 108, 111]);

// Hex
const hex = Array.from(bytes).map(b => b.toString(16).padStart(2, "0")).join("");
// "48656c6c6f"

// Base64
const base64 = btoa(String.fromCharCode(...bytes));
// "SGVsbG8="

Neither is encryption. Both are trivially reversible and provide no security. They are encoding formats, not cryptographic operations.