Your opening stock is the stock value (at cost) that you carry at the beginning of the period you are budgeting for. For our example here this would be at the beginning of July 2020.
If you were budgeting for a period that starts tomorrow, this would have been your current stock value (at cost). However; since we always budget for a period well in advance (usually 6 months ahead) this would mean calculating your opening stock well in advance.
Note: If you are using the Open to Buy excel sheet, you don’t need to perform the below calculation manually. You will enter the beginning inventory for Jan 2020, and afterwards the opening and closing stocks will be calculated automatically, based on the sales figures and intakes you provide.
To manually calculate the opening stock, check the example below:
You are now in Jan 2020 and want to budget for July 2020 to Dec 2020. You will need to get the opening stock for July 2020.
This will require you to extract the current stock on hand that you have (at Jan 2020) and then subtract from it any stocks that you will sell from Jan to June 2020 and add to it any stock that will arrive between Jan to June 2020.
Example
Current stock level (Jan 2020) at cost = 100,000$
Sales from Jan to June are 200,000$ at 60% margin
COGS from Jan to June = 200,000 $ x (1-0.6) = 200,000 x 0.4 = 80,000 $
Receiving (orders) that will arrive in March 2020 at cost = 20,000 $
Opening stock at July 2020 = 100,000 $ – 80,000 $ + 20,000 $ = 40,000 $