Which quantity is not required in order to calculate the mass of an ion using a mass spectrometer?

To calculate the mass of an ion using a mass spectrometer, the specific charge of the ion is not required. The mass-to-charge ratio (m/z) is measured directly, allowing for the determination of mass when the charge state is known. However, knowing the exact charge is not essential for calculating the mass itself, as the mass spectrometer provides the m/z value directly.