Weighted average method, also known as one-time weighted average method, refers to the method of calculating the weighted average unit cost of inventory by taking the total purchase amount of the current month plus the inventory amount at the beginning of the month as the weight, excluding the total purchase cost of the current month plus the inventory cost at the beginning of the month, and based on this, calculating the inventory cost issued in the current month and the inventory cost at the end of the period. Inventory weighted average unit cost = (inventory cost at the beginning of the month+inventory cost purchased this month)/(inventory balance at the beginning of the month+inventory quantity purchased this month) inventory cost at the end of the month = inventory quantity at the end of the month × inventory weighted average unit cost = inventory quantity issued in the current period × inventory weighted average unit cost or = inventory cost at the beginning+inventory cost at the current period-inventory cost at the end of the period weighted average method. In market forecasting, it is a method of averaging different weights according to the different importance of each data during the observation period. Its characteristic is that the average value includes long-term trend changes. Advantages and disadvantages of the weighted average method: Advantages: The calculation method is simple. Disadvantages: it is not conducive to the timeliness of accounting; In the case of large price changes, the ending inventory value calculated by weighted average unit price is quite different from the current cost applicable to the case of small price changes. A 34 yuan bought 10 eggs and B 45 yuan bought 20 eggs. What is the average price of eggs A and B? At this time, the arithmetic average can't be directly used as (34+45)/2, because they buy different quantities, so to calculate their average price, they can only use the quantity they buy as the weight and carry out weighted average: (34×10+45× 20)/(10+20) = 65430.