Space utilization uses the average row size and number of rows to compute the expected minimum number of data pages, and compares it to the current number of pages. If space utilization is low, running reorg rebuild on the table or dropping and re-creating the clustered index can reduce the amount of empty space on data pages, and the number of empty pages in extents allocated to the table.
If you are using space management properties such as fillfactor or reservepagegap, the empty space that is left for additional rows on data pages of a table with a clustered index and the number of empty pages left in extents for the table affects the space utilization value.
If statistics have not been updated recently and the average row size has changed or the number of rows and pages are inaccurate, space utilization may report values greater than 1.0.
