Inventory Turn is the Cost of Goods Sold over a period of time divided by the current Inventory Value.  For example, if a typical turn ratio is between 4 and 6 and if the inventory value is 1,000,000 then the COGS should be somewhere between 4 and 6 million.  This is not a hard thing to calculate in total, but this report is useful because it allows you to report by location, mfr and even by part number if desired. 

Important note: the cost of goods sold for the time period (usually one year but it can be less) and the inventory value must be accurate and complete for this report to be meaningful.