Abstract: Methods, systems, and computer-readable media for sizing a population of nucleic acid fragments. In an exemplary method of sizing a population of nucleic acid fragments provided by a sample, partitions may be formed, each containing a portion of the sample. Each target of at least two targets may be present in only a fraction of the nucleic acid fragments. Amplification reactions may be performed for each of the at least two targets in the partitions. Amplification data may be collected for the at least two targets from the partitions. Target-defined subsets of the partitions may be enumerated using the amplification data. At least one length characteristic of the population of nucleic acid fragments may be predicted using results of enumerating.