Days Inventory Outstanding (DIO) Calculator
From average inventory and cost of goods sold, compute how many days inventory sits before being sold (DIO).
輸入資料
計算結果
重點速覽：DIO = average inventory / COGS x period days (365 for a year). It shows the average days inventory sits before sale — lower = faster turnover, less tied capital; higher = slow stock, possible overstock. Right level varies by industry (fresh food very low, furniture/cars higher). WARNING: DIO doesn't reveal stockouts; compare within industry and watch seasonality. Education, not advice.
計算公式
DIO = 平均存貨 ÷ 銷貨成本 × 期間天數。
$$DIO = \dfrac{\text{平均存貨}}{\text{銷貨成本}} \times \text{期間天數}$$$$\text{存貨周轉率} = \dfrac{\text{銷貨成本}}{\text{平均存貨}}$$使用說明
- Enter the average inventory.
- Enter the COGS for the same period.
- Enter the period days (365 for a year) for DIO.
年銷貨成本固定為 HK$2,190,000 (365 天) 時，不同平均存貨對應的 DIO
| 平均存貨 | 年銷貨成本 | 存貨周轉天數 (DIO) | 解讀 |
|---|---|---|---|
| HK$300,000 | HK$2,190,000 | 50 天 | 周轉快，存貨管理佳 |
| HK$450,000 | HK$2,190,000 | 75 天 | 偏健康 |
| HK$600,000 | HK$2,190,000 | 100 天 | 中等，資金佔用漸增 |
| HK$750,000 | HK$2,190,000 | 125 天 | 偏長，留意積壓 |
| HK$900,000 | HK$2,190,000 | 150 天 | 周轉慢，資金積壓大 |
理財情境案例
案例一：由 DIO 看存貨周轉速度
一家貿易商年銷貨成本 HK$2,190,000，平均存貨 HK$600,000。DIO = 600,000 ÷ 2,190,000 × 365 = 100 天，即存貨平均約 100 天才周轉一次;換算存貨周轉率 = 365 ÷ 100 ≈ 3.65 次/年。
這代表公司資金平均被存貨鎖住約 100 天。若能透過需求預測與採購優化把 DIO 縮短到 75 天，就能釋放一部分營運資金。
結論：DIO 把抽象的『存貨周轉率』轉成直觀的天數，方便與 DSO、DPO 相加減計算現金轉換週期。
案例二：兩間同業的存貨效率對比
同樣年銷貨成本 HK$2,190,000。A 店採精實庫存，平均存貨 HK$300,000，DIO = 50 天;B 店習慣囤貨，平均存貨 HK$900,000，DIO = 150 天。
A 店的存貨資金佔用只有 B 店的三分之一，周轉快、貶值與滯銷風險低。但要留意 A 店的 DIO 是否過短導致缺貨 — 需結合缺貨率一起看。
結論：DIO 差距揭示兩者營運資金效率的懸殊。B 店若能把 DIO 降下來，可大幅釋放被存貨佔用的現金。
常見問題
What is DIO and how is it computed?
DIO (Days Inventory Outstanding) = average inventory / COGS x period days (365 for a year). Example: average inventory 1,000,000, annual COGS 6,000,000, 365 days → (1,000,000/6,000,000)x365 ≈ 60.8 days. It tells how long inventory sits on average before sale.
How is DIO linked to inventory turnover?
They are inverses: turnover = COGS / average inventory (times per year); DIO = 365 / turnover (days per turn). High turnover = low DIO (fast); low turnover = high DIO (slow). They express the same efficiency from different angles.
What is a good DIO, and does a lower number mean better?
There is no universal good level — it depends on industry. Fresh food must be very low; furniture, cars, heavy equipment are naturally higher. Lower is not always better: too low risks stockouts and lost sales; too high risks obsolescence and tied capital. Judge against peers and your own trend.
What is the relationship between DIO and inventory turnover?
They are two faces of the same coin: turnover = COGS / average inventory (how many times inventory sells per year); DIO = period days / turnover (average days to sell one round). So DIO = (average inventory / COGS) x days. High turnover → low DIO → fast; low turnover → high DIO → slow. Use whichever angle you prefer, but be consistent on the period (annual vs quarterly).
What are the Hong Kong SME pain points, and caveats?
HK SMEs (retail, F&B, trading) often tie large working capital in inventory; rent is high, so slow stock raises cost and risk. Pain points: overstock from misjudged demand, dead stock from seasonal/off-style goods, cash-flow strain during long inventory cycles. Caveats: (1) DIO alone doesn't show stockouts — pair with service level; (2) compare within industry and same period (seasonality distorts); (3) use average inventory, not just closing; (4) FIFO vs weighted-average COGS affects the number. The HKTDC and HKPC offer inventory and working-capital guidance. Education, not advice.
相關工具
參考資料
內容審核：香港計算器財經團隊。計算邏輯與公式參考香港金融管理局（HKMA）及投資者及理財教育委員會（IFEC）之個人理財計算指引，結果僅供參考，實際以相關機構公佈為準。