The size at which you should print your QR code depends on various factors including its use case, the distance from which it will be scanned, and the amount of data it encodes. Here are a few guidelines to consider:
Scanning Distance: As a general rule of thumb, the size of the QR code should be 1/10th of the scanning distance. For example, if you expect the code to be scanned from a distance of 10 inches, the QR code should be at least 1 inch x 1 inch.
Data Density: QR codes that encode more data will have more modules (small black squares). To ensure that these remain scannable, the QR code might need to be printed larger.
Use Case: Consider where the QR code will be used. For instance, QR codes on business cards can be around 1 inch x 1 inch (2.5 cm x 2.5 cm), whereas QR codes on posters or billboards might need to be much larger.
Printing Resolution: Ensure that the QR code is printed at a high resolution. This is especially important for smaller QR codes, as a lower resolution could make them unscannable.
Error Correction: QR codes with a higher level of error correction can be smaller since they are more resilient to being partially obscured or damaged. However, higher error correction means encoding less data in the same space, so it can also sometimes mean needing a larger code for the same data.
Testing: Before finalizing the size, print a test QR code and try scanning it with different devices. This will help you confirm if the size is appropriate for the intended use.
In summary, there is no one-size-fits-all answer, and the optimal size for a QR code can vary based on its application. However, a size of around 1 inch x 1 inch (2.5 cm x 2.5 cm) is often sufficient for general use cases like business cards or flyers. For use in environments where the scanning distance is longer, such as posters or display signs, the QR code will need to be proportionally larger.