@towhidctg @MirriamM 

If you're referring to Invoices for Inventory Type items, you can run the "Transaction Journal" for that specific Invoice as mentioned here and get the Gross Profit number. But there is no one standard summary report that will give the Gross Profit by each Invoice line.

Note: Inventory type is available in Plus and Advanced only. In other plans (Essentials and Simple Start), the Inventory item details feature is not available.