Analyte monitors and their methods of use. The analyte monitors include multiple calibration fluids which may have different known concentrations of an analyte, such as glucose. The analyte monitors may also include sensing or washing fluids. The analyte monitors are configured to be calibrated with the multiple calibration fluids to potentially provide a more accurate determination of analyte concentrations. The analyte monitors can be adapted to be self-calibrating with the multiple calibration fluids.