How large does a racking label barcode need to be for high-level storage?

Size follows the X-dimension the scan distance demands. A 15 mil Code 128 symbol is decodable to under two metres, while reaching beyond seven metres calls for an X-dimension in the 55 mil range or above, which makes a twelve-character symbol several hundred millimetres wide. Confirm the working range published for the specific scan engine in use before fixing a label size.