Abstract: Methods, compositions, and kits for analyzing viral particles. In an exemplary method of analyzing viral particles, capsids of the viral particles may be tagged with a tag. Subsamples of a sample containing the viral particles may be formed. Each subsample of only a subset of the subsamples may include at least one of the viral particles. One or more targets may be amplified from a genome of the viral particles. Tag-related data, and amplification data for the one or more targets, may be collected from the subsamples. In some examples, a capsid occupancy of the viral particles may be determined in a calibration-free approach using the collected data without quantification of the viral particles or capsids thereof.