The claimed subject matter relates to an architecture that can determine costs associated with updating file formats. In particular, the architecture can interface with a network-accessible data storage service in order to determine a cost-benefit to the data storage service for a wide variety of conversion scenarios applicable to the particular topology of the data storage service. For example, the cost-benefit can differ for storage services configured according to a client-server model relative to storage services configured according to a distributed topology. Regardless, the architecture can identify a legacy format, select a converter for converting the legacy format to the updated format, and then determine the cost-benefit for a variety of conversion or migration scenarios.