Base64とHex（16進数）の主な違い
Both Base64 and Hex (Hexadecimal) are binary-to-text encoding methods used to represent raw byte sequences as text strings. However, their size efficiency and character sets differ significantly.
| Feature | Base64 | Hexadecimal (Hex) |
|---|---|---|
| Alphabet Size | 64 characters (A-Z, a-z, 0-9, +, /) | 16 characters (0-9, A-F) |
| Size Expansion | +33.3% overhead | +100% overhead (2x size) |
| Bits per Character | 6 bits | 4 bits (nibble) |
| Primary Use Cases | Email attachments (MIME), Data URLs, JWT payloads, API responses | Cryptographic hash outputs (SHA256, MD5), memory inspection, MAC addresses |
HexではなくBase64を選択すべき場合
Choose Base64 when payload size matters. Because Base64 expands binary data by only ~33% compared to Hex's 100% expansion, Base64 saves significant network bandwidth when embedding images, converting documents, or sending large API payloads.
Learn more in our main What is Base64 Guide or test conversion live with our Hex ↔ Base64 Converter Tool.