Inventory change is the difference between last period's ending inventory and the current period's ending inventory. If last period's ending inventory was $100,000 and the current period's ending inventory is $115,000, the inventory change is an increase of $15,000.
The inventory change is often presented as an adjustment to purchases in the calculation of the cost of goods sold. If purchases were $300,000 during the current period and the inventory amounts are those listed above, the cost of goods sold is $285,000. (Purchases of $300,000 minus the $15,000 increase in inventory. The logic is that not all $300,000 of purchases should be matched against sales, because $15,000 of the purchases went into inventory.) This is an alternative to the method used in introductory accounting: beginning inventory of $100,000 + purchases of $300,000 = $400,000 of cost of goods available – ending inventory of $115,000 = cost of goods sold of $285,000.
If last period's ending inventory was $100,000 and the current period's ending inventory is $93,000, the inventory change is a decrease of $7,000. Assuming purchases of $300,000 in the current period, the cost of goods sold is $307,000 ($300,000 of purchases plus the $7,000 decrease in inventory).