Enhanced Inventory Facts
The simplistic view of inventory we developed in our periodic snapshot fact
table allows us to see a time series of inventory levels. For most inventory
analysis, quantity on hand isn’t enough. Quantity on hand needs to be used in
conjunction with additional facts to measure the velocity of inventory movement
and develop other interesting metrics such as the number of turns, number
of days’ supply, and gross margin return on inventory (GMROI,
pronounced “jem-roy”).
If we added quantity sold (or equivalently, quantity depleted or shipped if
we’re dealing with a warehouse location) to each inventory fact row, we could
calculate the number of turns and days’ supply. For daily inventory snapshots,
the number of turns measured each day is calculated as the quantity sold
divided by the quantity on hand. For an extended time span, such as a year,
the number of turns is the total quantity sold divided by the daily average
quantity on hand. The number of days’ supply is a similar calculation. Over a
time span, the number of days’ supply is the final quantity on hand divided by
the average quantity sold.
讀了上邊的原文，再讀下下邊的可能就可以理解了
二、庫存週轉率的評析
庫存週轉率對於企業的庫存管理來說具有非常重要的意義。例如製造商，它的利益是由資金→原材料→產品→銷售→資金的循環活動中產生的，如果這種循環很快也就是週轉快時，在同額資金下的利益率也就高。因此，週轉的速度代表了企業利益的測定值，被稱爲“庫存週轉率”。
對於庫存週轉率，沒有絕對的評價標準，通常是同行業相互比較，或與企業內部的其他期間相比擬分析。庫存績效評價與分析，庫存週轉率是着重評價的內容。
（一）庫存週轉率的基本計算公式
庫存週轉率的計算公式，實際評價中可用如下公式進行計算：
庫存週轉率=（使用數量/庫存數量）×100%
使用數量並不等於出庫數量，因爲出庫數量包括一部分備用數量。除此之
外也有以金額計算庫存週轉率的。同樣道理使用金額並不等於出庫金額。
庫存週轉率=（使用金額/庫存金額）×100%
使用金額也好，庫存金額也好，是何時的金額，因此規定某個期限來研究金額時，需用下列算式：
庫存週轉率=（該期間的出庫總金額/該期間的平均庫存金額）×100%
=（該期間出庫總金額×2/期初庫存金額+ 期末庫存金額）×100%
庫存週轉率計算公式是(以月平均庫存週轉率爲例)：
1、原材料庫存週轉率＝月內出庫的原材料總成本/原材料平均庫存
2、在制庫存週轉率＝月內入庫的成品物料成本/平均在制庫存
3、成品庫存週轉率＝月銷售物料成本/成品在庫平均庫存
例如：
Inventory Turnover
= Cost of goods sold/Average aggregate inventory value
= $160/$35
= 4.57
庫存週轉率 = 售出商品的成本 / 平均庫存總值 = 160 / 35 = 4.57
Since the company is used to an inventory turnover of 10, a drop to 4.57 means
that the inventory is not turning over as quickly as it had in the past. Without
knowing the industry average of turns for this company it is not possible to
comment on how they are competitively doing in the industry.
由於該公司的庫存週轉率往年是10 , 這年降低至4.57 , 則意味着
它的庫存週轉沒有以往那麼快。如果不知道這家公司所在行業的
平均週轉率，是不可能評論它在行業中有多少競爭力的。