Disclosed herein are methods for estimating the copy number of a target chromosome in a sample. In some embodiments, the methods include: partitioning a sample comprising one or more copies of the first target chromosome, into a plurality of partitioned samples; stochastically barcoding the one or more copies of the first target chromosome in the plurality of partitioned samples using a first plurality of stochastic barcodes, wherein each of the first plurality of stochastic barcodes comprises a first chromosome label and a first molecular label; and estimating the copy number of the first target chromosome in the sample using the first chromosome label and the second molecular label. The disclosed methods can be used for haplotype phasing, aneuploidy determination, and DNA sequencing.