Electrospray ionization (ESI) mass spectrometry (MS) is an essential technique in chemical analysis, enabling a diverse range of environmental, industrial, and biological applications. One benefit of ESI is that it imparts multiple charges to analytes, which enables larger species to be analyzed on instruments with limited m/z ranges. Even on instruments with higher m/z ranges, having multiple charge states aids in fragmenting molecules for different applications. However, the presence of different charge states complicates data analysis because the charge must be assigned to determine the mass. For low resolution data, with resolved charge states but unresolved isotope distributions, multiple approaches have been developed to determine the charge from the spacing between adjacent charge states. For unresolved data lacking resolved charge state distributions, charge detection-mass spectrometry can be used to directly measure the charge on individual ions. For high resolution data with resolved isotope distributions, the spacing between adjacent isotopes is used for charge determination.