Calibrants and methods of making the same include using mixtures of multifunctional core compounds or multifunctional dendrimers that are functionalized to yield a set of discrete compounds which cover a range of collisional cross sections (CCSs) for calibrating ion mobility and variation in molecular weight to calibrate the mass to charge (m/z) measurements of mass spectrometry, as well as for calibrating tandem instruments that measure both dimensions. Methods of using the calibrants are also disclosed, such as in mass spectrometry.