Systems and methods for sampling a set of block IDs to facilitate estimating an amount of data stored in a data set of a storage system having one or more characteristics are provided. According to an example, metadata (e.g., block headers and block IDs) may be maintained regarding multiple data blocks of the data set. When one or more metrics relating to the data set are desired, an efficiency set, representing a subset of the block IDs of the data set, may be created to facilitate efficient calculation of the metrics by statistically sampling the block IDs of the data set. Finally, the metrics may be estimated based on the efficiency set by analyzing one or more of the metadata (e.g., block headers) and the data contained in the data blocks corresponding to the subset of the block IDs and extrapolating the metrics for the entirety of the data set.