Byte

A byte is a fundamental unit of digital data consisting of 8 bits, capable of representing 256 values (0 to 255). In computing, bytes measure file sizes, memory capacity, and data transfer rates. In the QR code context, bytes appear in data capacity specifications and as the encoding unit for Binary Mode.

In Binary Mode, input data is stored one byte at a time. ASCII characters (letters, digits, symbols) use 1 byte each, while UTF-8 Japanese characters consume 3 bytes each. The maximum capacity at Version 40 (largest size) with error correction level L is 2,953 bytes - equivalent to roughly 2,953 ASCII characters or about 984 Japanese characters.

In practice, estimating the byte count of your data before generating a QR code is essential. A typical URL is 50-100 bytes, but UTM parameters can push it past 200 bytes. A vCard with just name, phone, and email runs 200-300 bytes; adding address and company can exceed 500 bytes. More bytes mean a larger QR code version, making it harder to print in small spaces.