Abstract: Aspects of the present disclosure generally relate to data storage devices, systems, and related methods that determine writing fragmentation levels of memory devices, such as memory devices of solid-state drives (SSDs). In one aspect, a controller of a data storage device is configured to determine a plurality of valid counts of a plurality of blocks of one or more memory devices, and arrange the plurality of valid counts of the plurality of blocks into a plurality of valid count groupings. The plurality of valid counts is arranged into a histogram having the plurality of block counts and the plurality of valid count groupings. In one aspect, the controller is configured to multiply the plurality of block counts by a plurality of assigned weights to determine a plurality of writing fragmentation values. In one aspect, the controller is configured to determine a writing fragmentation level.