JIS

JIS (Japanese Industrial Standards) is Japan's national standards framework for industrial products and services. For QR codes, the most relevant standard is JIS X 0208, which defines the character set used by Kanji mode.

Kanji mode encodes each of the roughly 6,879 characters in JIS X 0208 (kanji, hiragana, katakana, and symbols) using just 13 bits. By comparison, UTF-8 typically requires 24 bits (3 bytes) per Japanese character. This efficiency means more Japanese text fits into a smaller QR code - a direct benefit of QR codes having been invented in Japan.

Characters outside JIS X 0208 - emoji, certain name-use kanji, simplified Chinese characters - cannot use Kanji mode and fall back to Byte mode, which requires more bits per character and increases code size. When encoding Japanese text in a QR code, checking whether all characters fall within JIS X 0208 helps produce the most compact code possible.