avg_page_space_used_in_percent and fill factor sys.dm_db_index_physical_stats contains column avg_page_space_used_in_percent.

How does this fit in with the fill factor of an index?

For example:

I have index idx_HeaderInfo

I create the index with a fill factor of 80%.

If I then immediately look at avg_page_space_used_in_percent do I see:


100
80


I ask because I need a way of rebuilding or reorganising based on internal fragmentation rather than external and I don't want to create logic to rebuild/reorg if a avg_page_space_used_in_percent &lt; 75 if the fill factor in the first place is 70 for instance.
avg_page_space_used_in_percent does not care about fill factor. 

Therefore if you set an index to have fill factor of 40, your avg_page_space_used_in_percent will straight away be 40.