Need help measuring inventory levels

Hi good people. I need help calculating the Work In Progress (WIP) inventory for my work.

My Excel spreadsheet has three columns.
- Column A is the item’s unique identification code
- Column B is the time that the item entered the warehouse
- Column C is the time that the item left the warehouse

Could you help me create an Excel formula in Column D that calculates the inventory in the warehouse at the time of the item’s entry into the warehouse?

For example, if item 84363884U entered the store at 09:07:23, I would like to know the inventory levels in the warehouse at 09:07:23.

Here is an attached Excel file for reference. Please and thank you.

Calculating WIP.xlsx

Try, in D2 copy down: =COUNTIFS($B$2:$B$1000,"<="&B2,$C$2:$C$1000,">="&B2)