A test strip for the determination of an analyte, such as glucose, in a body fluid sample (for example, a whole blood sample) includes a substrate with a working surface for receiving the body fluid sample and a reverse surface that is in opposition to the working surface. The test strip also includes a permutative grey scale calibration pattern disposed on either of the working and reverse surfaces with the permutative grey scale calibration pattern including more than one grey scale region. Moreover, the scale regions of the test strip define a grey scale permutation that uniquely corresponds to a calibration code of the test strip.