Stock-to-sales ratio is an index to check whether the inventory is reasonable, such as monthly stock-to-sales ratio and annual average stock-to-sales ratio. The calculation methods are: monthly inventory-to-sales ratio, monthly average inventory/monthly average inventory/annual sales ratio, and annual average inventory/annual sales ratio. A high proportion means that the inventory is too large and the sales are not smooth. If it is too low, it may be that the output cannot keep up.