Virtual storage free space management techniques may calculate a data allocation value of a virtual storage entity based on a number of storage slabs allocated with data. The virtual storage free space management techniques may further analyze a physical storage entity to determine a storage allocation value associated with the physical storage entity. The storage allocation value may be obtained by summing the storage amount in bytes associated with each of the storage slabs of the physical storage entity that is allocated to one or more virtual storage entities. A free space value associated with the virtual storage entity may be determined based on the storage allocation value and the data allocation value.