In this webinar, we demonstrate how the mass of AAV capsids can be determined using two different novel, emerging single-particle techniques: Charge-detection mass spectrometry (CDMS) and mass photometry. In contrast to ensemble-based approaches (e.g. native mass spectrometry), mass photometry and CDMS can measure the mass of numerous, individual AAV particles, circumventing issues driven by sample heterogeneity. Detection of AAVs’ charge and mass-over-charge ratio was done on an Orbitrap mass analyzer (the Q Exactive™ UHMR), commonly used for macromolecular analysis, while mass photometry, based on the microscopic detection of particle’s induced light scattering, was done on a recently developed AAV-dedicated mass photometer (the SamuxMP).