A method for determining a test strip calibration code for use in a meter includes inserting a calibration strip into the meter, with the calibration strip having a substrate and a permutative grey scale calibration pattern disposed on the substrate. In addition, the permutative grey scale calibration pattern includes more than one grey scale region that define a grey scale permutation uniquely corresponding to a calibration code of test strips in a package associated with the calibration strip. The method also includes: (i) detecting the permutative grey scale calibration pattern with a grey scale photodetector module of the meter, and (ii) determining a calibration code that uniquely corresponds to a grey scale permutation defined by the permutative grey scale calibration pattern based on a permutation matrix stored in the meter.