What are inventory and cost of sales?
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Inventory and cost of sales are two closely related and important concepts in Prinsip Perakaunan, especially for a business that buys and sells goods. Understanding them helps students work out gross profit correctly.
What inventory is
Inventory, or stock, is the goods a business has bought for resale but not yet sold by the end of the period. It is treated as a current asset because it is expected to turn into cash when sold soon.
What cost of sales is
Cost of sales is the cost of the goods sold during the period, not all the goods bought. It is subtracted from sales to get gross profit, so calculating it accurately matters for a correct statement.
The cost of sales formula
Cost of sales is worked out as: opening stock + purchases − closing stock. The idea is simple: from all the goods available for sale, subtract what’s still left, and the remainder is the cost of the goods that were sold.
Why closing stock matters
Closing stock appears in two places: it reduces cost of sales in the income statement, and it is listed as a current asset in the statement of financial position. An error in closing stock affects both statements at once.
Effect on gross profit
Gross profit is sales minus cost of sales. If cost of sales is worked out too high, gross profit looks too low, and vice versa. That is why stock and purchases must be calculated accurately.
Stock valuation in brief
Stock is usually valued at the lower of cost or net realisable value, to avoid overstating the asset. For details of the valuation method required, refer to the official syllabus documents.
Common student mistakes
Common mistakes include forgetting to subtract closing stock, mixing up purchases with sales, or wrongly including a cost that isn’t part of the cost of goods. Each one changes gross profit.
The link with the income statement
The first part of the income statement works out gross profit using sales and cost of sales. Understanding inventory and cost of sales makes this part much easier to grasp and answer confidently.
Try it yourself
Take a simple set of figures (opening stock, purchases and closing stock) and work out cost of sales and gross profit. Our teachers can guide students through examples like this in online 1-to-1 lessons. A paid trial class can be booked on WhatsApp.
FAQ
What is the cost of sales formula? Opening stock + purchases − closing stock. It represents the cost of the goods sold during the period.
Why does closing stock appear in two places? It reduces cost of sales in the income statement and is listed as a current asset in the statement of financial position.
How does cost of sales affect profit? Gross profit is sales minus cost of sales, so an error in cost of sales directly affects the reported gross profit.