加重平均原価法

Weighted average costing divides the total cost of all goods available for sale by the total number of units available. For example, if a company purchases 400 units across three batches totaling $4,800, the weighted average cost per unit is $12. This single average cost is then applied uniformly to all units, regardless of which batch they came from.

Weighted average costing pools all inventory costs together and assigns a single per-unit cost to every unit sold. By averaging costs across all batches, it avoids the timing sensitivities of methods like FIFO or LIFO. This stabilizing effect is particularly useful in markets where purchase prices fluctuate due to supplier changes or demand cycles.

Cost of goods sold is calculated by multiplying the weighted average cost per unit by the quantity of units sold. For instance, if TechGadget sells 100 units at a weighted average cost of $12 per unit, the cost of goods sold is $1,200. This uniform treatment applies regardless of which inventory batch the units originated from.

Weighted average costing offers simplicity in both manual and automated accounting systems by applying one consistent per-unit cost to all units. It avoids the complexity of tracking individual batches and is well-suited for industries with high inventory turnover and indistinguishable goods. This straightforward approach simplifies forecasting and cost analysis.

Ending inventory is valued by multiplying the weighted average cost per unit by the number of units remaining. Since all units carry the same average cost regardless of purchase batch, ending inventory valuation is consistent and predictable. This uniform treatment directly impacts the cost of goods sold calculation and overall financial reporting accuracy.

Weighted average costing is particularly well-suited for industries where goods are not individually traceable and inventory turnover is high. It works best when items are indistinguishable or frequently intermingled, and when purchase prices fluctuate regularly. The method's simplicity makes it ideal for companies seeking consistent, straightforward inventory management without complex batch tracking.

Unlike FIFO or LIFO, weighted average costing does not assign higher or lower costs based on the timing of purchases or sales. Instead, it pools all costs together into a single per-unit average. This approach avoids the timing sensitivities inherent in other methods, making it a more neutral and consistent choice for companies with fluctuating purchase prices.