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What is days inventory outstanding?什么是存货周转天数？
Days inventory outstanding (DIO) equals average inventory divided by cost of goods sold (COGS), multiplied by the number of days in the matching period. It expresses the inventory-to-COGS relationship as an estimated number of days.
存货周转天数（DIO）等于平均库存除以同一期间的销售成本（COGS），再乘以该期间天数。它把库存相对销售成本的关系表达为估算天数。
DIO is also called inventory days, days in inventory, days sales in inventory, or the inventory period. In practice, these terms often describe the same cost-based efficiency measure. Always inspect the published formula: some organizations use ending inventory instead of average inventory, a 360-day convention instead of actual days, or a sales denominator. Those choices create different values even when the label looks identical.
DIO 也常被称为库存天数、存货天数、库存销售天数或库存期间。实践中，这些词通常指同一项以成本为基础的效率指标。但必须检查实际公式：有些组织用期末库存代替平均库存，用 360 天代替实际天数，或使用销售收入作为分母。即使指标名称相同，这些选择也会产生不同结果。
DIO is not a literal promise that every unit sells after that many days. It is an aggregate estimate based on inventory value and the rate at which cost flows through COGS. A business can report 50 DIO while individual lots range from one day to several years. For physical age, expiry, and slow-moving analysis, use lot receipt dates and movement history alongside DIO.
DIO 并不表示每件商品恰好在该天数后售出。它是根据库存价值以及成本进入销售成本的速度得到的汇总估计。企业可能报告 50 天 DIO，但具体批次的库龄可能从一天到数年不等。分析实际库龄、到期和慢动库存时，应把批次收货日期与移动历史和 DIO 结合。
Inputs and conventions required for a reliable DIO calculation可靠计算 DIO 所需的数据与口径
A simple average is beginning plus ending inventory divided by two. Use monthly, weekly, or daily snapshots when inventory is seasonal or volatile.
简单平均值为期初与期末库存之和除以二。季节性或波动较大时，应使用月度、周度或每日快照。
Use cost of goods sold, not revenue, purchases, supplier payments, or the value of orders placed. Keep the inventory scope consistent.
使用销售成本，而不是收入、采购额、供应商付款或下单金额，并保持库存范围一致。
Use 365 or 366 for a year, the actual days in a month or quarter, or a documented 360-day management convention applied consistently.
年度可用 365 或 366 天，月度或季度使用实际天数；也可采用有记录且始终一致的 360 天管理口径。
Define entities, currencies, warehouses, and whether raw materials, work in progress, finished goods, consignment, and in-transit inventory are included.
明确实体、币种、仓库，以及是否包含原材料、在制品、产成品、寄售和在途库存。
Reconcile inventory snapshots to controlled finance reports before calculation. Investigate returns, write-downs, obsolescence, acquisitions, transfers, standard-cost revaluations, and exchange-rate changes. A lower ending balance caused by a write-down can reduce DIO without improving physical movement. A consistent metric contract is more valuable than extra decimal places.
计算前，应把库存快照与受控财务报表核对，并调查退货、减值、报废、并购、调拨、标准成本重估和汇率变化。减值导致的期末余额下降可能降低 DIO，却没有改善实物流动。稳定一致的指标契约比增加小数位更重要。
Days inventory outstanding example, step by step存货周转天数完整计算示例
Assume a hypothetical distributor reports annual COGS of $3,650,000, beginning inventory of $550,000, and ending inventory of $650,000. These figures are illustrative and are not customer or product claims.
假设一家虚构经销商的年度销售成本为 3,650,000 美元，期初库存为 550,000 美元，期末库存为 650,000 美元。这些数字仅用于演示，不代表任何客户或产品数据。
- Calculate average inventory计算平均库存($550,000 + $650,000) ÷ 2 = $600,000.（550,000 + 650,000）÷ 2 = 600,000 美元。
- Divide average inventory by COGS平均库存除以销售成本$600,000 ÷ $3,650,000 = 0.16438.600,000 ÷ 3,650,000 = 0.16438。
- Multiply by period days乘以期间天数0.16438 × 365 = 60.0 days inventory outstanding.0.16438 × 365 = 60.0 天存货周转天数。
- Cross-check with turnover用周转率交叉验证COGS ÷ average inventory = 6.083 turns; 365 ÷ 6.083 also equals approximately 60.0 days.销售成本 ÷ 平均库存 = 6.083 次；365 ÷ 6.083 同样约等于 60.0 天。
Interpretation: the company carried inventory value equal to about 60 days of annual COGS on average. This does not prove each SKU took 60 days to sell, nor does it prove that 60 is good. Compare it with prior periods, plans, service levels, category economics, and compatible peers.
解读：该公司平均持有的库存价值约相当于 60 天的年度销售成本。这不证明每个 SKU 都需要 60 天售出，也不证明 60 天一定良好。应与历史期间、计划、服务水平、品类经济性和可比同行共同比较。
Days inventory outstanding calculator存货周转天数计算器
Enter inventory and COGS measured on the same cost basis and for the same period. The calculation runs locally in your browser. The simple two-point average is suitable for stable inventory; use periodic snapshots outside this calculator when seasonality or rapid growth makes the endpoints unrepresentative.
请输入采用相同成本口径并对应同一期间的库存和销售成本。计算在浏览器本地完成。两点平均法适用于稳定库存；当季节性或快速增长使期初期末余额缺乏代表性时，应在本计算器外使用周期快照平均值。
DIO, inventory turnover, DSI, and inventory ageDIO、库存周转率、DSI 与实际库龄的区别
| Metric指标 | Answers回答的问题 | Main caution主要注意 |
|---|---|---|
| DIO / inventory days | How many days of COGS the average inventory represents.平均库存相当于多少天销售成本。 | Aggregate estimate; not actual lot age.属于汇总估计，并非实际批次库龄。 |
| Inventory turnover库存周转率 | How many cost-based inventory cycles occur per period.一个期间内库存按成本周转多少次。 | Inverse of DIO when period and scope match.期间与范围一致时，与 DIO 互为倒数表达。 |
| Days sales in inventory | Often used as a synonym for DIO.通常作为 DIO 的近义表达。 | Verify whether the denominator is COGS or sales.必须核对分母究竟是销售成本还是销售额。 |
| Inventory aging实际库龄 | How long specific lots or units have remained since receipt or movement.具体批次或单位自收货或移动以来存放多久。 | Requires reliable lot and movement timestamps.需要可靠的批次与移动时间戳。 |
The related inventory turnover ratio guide explains the cycles-based view in depth. When the two pages are deployed together, they should cross-link because users often move between “times per year” and “days held” while investigating the same inventory balance.
相关的库存周转率指南深入解释按周转次数观察的视角。两页共同部署后应互相链接，因为用户分析同一库存余额时，经常在“每年周转次数”和“持有天数”之间转换。
Where DIO fits in the cash conversion cycleDIO 在现金转换周期中的位置
DIO is the inventory component of the cash conversion cycle (CCC): CCC = DIO + days sales outstanding (DSO) − days payable outstanding (DPO). In simplified terms, inventory days cover time before sale, DSO covers time from sale to customer collection, and DPO offsets the time the company takes to pay suppliers.
DIO 是现金转换周期（CCC）的库存部分：CCC = DIO + 应收账款周转天数（DSO）− 应付账款周转天数（DPO）。简化来说，DIO 覆盖售前库存时间，DSO 覆盖销售至客户回款的时间，而 DPO 抵减企业支付供应商所占用的时间。
A falling DIO can shorten the cash cycle and release working capital, but only if it does not shift cost elsewhere. Smaller, more frequent orders may reduce inventory while increasing freight and administrative cost. Leaner safety stock may release cash while increasing missed sales. Evaluate working-capital benefit together with margin, service, supplier risk, and total landed cost.
DIO 下降可能缩短现金周期并释放营运资金，但前提是没有把成本转移到其他环节。更小、更频繁的订单可能降低库存，却增加运费和管理成本；更低的安全库存可能释放现金，却提高销售损失。应把营运资金收益与毛利、服务、供应商风险和总到岸成本共同评估。
How to interpret high, low, and changing DIO如何解读高、低及变化中的 DIO
| Pattern表现 | Possible explanation可能解释 | Evidence to review需要检查的证据 |
|---|---|---|
| DIO falls; service stableDIO 下降，服务稳定 | Demand, assortment, forecasting, or replenishment may have improved.需求、组合、预测或补货可能改善。 | Margin, forecast bias, markdowns, lead time.毛利、预测偏差、降价和交期。 |
| DIO falls; stockouts riseDIO 下降，缺货上升 | Inventory may be too lean rather than efficient.库存可能过低，而不是更有效率。 | Fill rate, lost sales, backorders, expedite cost.满足率、销售损失、欠单和加急成本。 |
| DIO rises before peak season旺季前 DIO 上升 | Planned build may protect availability.计划性备货可能用于保障可得性。 | Seasonal plan, shelf life, sell-through, cash limits.季节计划、保质期、售罄率和现金限制。 |
| DIO rises in one category单一品类 DIO 上升 | Lifecycle decline, mix shift, forecast error, or excess buying.生命周期下行、组合变化、预测错误或过量采购。 | SKU aging, returns, promotions, purchase orders.SKU 库龄、退货、促销和采购订单。 |
There is no universal good DIO. Perishable food, fashion, spare parts, industrial equipment, pharmaceuticals, and project inventory operate with different shelf lives, margins, lead times, availability requirements, and risk. Benchmark within a compatible business model and calculation method, then prioritize the company's own trend and decision thresholds.
不存在适用于所有企业的良好 DIO。生鲜食品、服装、备件、工业设备、医药和项目库存具有不同的保质期、毛利、交期、可得性要求和风险。应在商业模式与计算方法一致的范围内比较，并优先关注企业自身趋势与决策阈值。
A reproducible DIO analysis workflow可复现的 DIO 分析工作流
- Define and version the metric定义指标并进行版本管理Record period days, cost basis, inventory classes, entities, currencies, snapshot method, and treatment of returns, transfers, write-downs, and in-transit inventory.记录期间天数、成本口径、库存类别、实体、币种、快照方法，以及退货、调拨、减值和在途库存的处理。
- Connect controlled sources连接受控数据源Combine finance COGS, ERP inventory snapshots, product and location masters, orders, shipments, purchase orders, suppliers, and service events.汇总财务销售成本、ERP 库存快照、产品和地点主数据、订单、发货、采购单、供应商及服务事件。
- Reconcile before calculation计算前完成核对Tie totals to controlled reports, remove duplicate snapshots, align time zones and currencies, and explain material adjustments.将总额与受控报表核对，删除重复快照，对齐时区和币种，并解释重大调整。
- Calculate and segment计算并分层Compute company DIO, then decompose by SKU, product family, warehouse, region, channel, supplier, lifecycle stage, and ABC class where cost allocation is reliable.先计算公司级 DIO，再在成本分配可靠时按 SKU、产品族、仓库、区域、渠道、供应商、生命周期和 ABC 分类拆解。
- Validate drivers and decisions验证驱动因素与决策Review changes with finance, planning, procurement, warehouse, and commercial owners. Test proposed actions against fill rate, margin, risk, and total cost.与财务、计划、采购、仓库和商业负责人共同复核变化，并用满足率、毛利、风险和总成本检验拟议行动。
Analyze DIO across connected inventory and finance data跨库存与财务数据分析 DIO
Prepare read-only access or exports for inventory snapshots, COGS, orders, shipments, products, warehouses, suppliers, and approved metric definitions. InfiniSynapse can support analysis across connected databases, warehouses, files, and documents so teams can ask which categories, locations, or suppliers changed DIO and inspect supporting records. It is an analysis layer—not an ERP, WMS, accounting system, purchasing application, or automatic replenishment engine. Responsible teams should validate calculations and operational decisions.
请准备库存快照、销售成本、订单、发货、产品、仓库、供应商及已批准指标定义的只读访问或导出文件。InfiniSynapse 可跨数据库、数据仓库、文件和文档开展联合分析，帮助团队追问哪些品类、地点或供应商改变了 DIO，并检查支持记录。它是分析层，不是 ERP、WMS、会计系统、采购应用或自动补货引擎。计算和运营决策仍应由责任团队验证。
Open InfiniSynapse for connected DIO analysis打开 InfiniSynapse 进行关联 DIO 分析Common DIO mistakes and practical improvement actionsDIO 常见错误与实操改进行动
- Mixing periods: monthly COGS cannot be paired with annual average inventory or multiplied automatically by 365.混用期间：月度销售成本不能与年度平均库存配对，也不能机械乘以 365。
- Using revenue as COGS: this mixes selling price with inventory at cost and changes the ratio.用收入代替销售成本：这会混合售价与成本库存，改变指标含义。
- Relying on year-end inventory: use periodic averages when seasonality or growth makes endpoints unrepresentative.只依赖年末库存：季节性或增长使端点失真时，应使用周期平均值。
- Comparing incompatible definitions: align day count, scope, valuation, industry, and service model first.比较不兼容定义：先对齐天数、范围、计价、行业和服务模式。
- Treating DIO as physical age: use lot-level aging for expiry and slow-movement decisions.把 DIO 当成实际库龄：到期和慢动决策应使用批次级库龄。
- Optimizing DIO alone: monitor service, stockouts, margin, lead time, risk, and total cost.只优化 DIO：还要监控服务、缺货、毛利、交期、风险和总成本。
Actions should follow diagnosis. Possible responses include correcting forecast bias, reducing minimum order quantities, changing order cadence, rationalizing slow SKUs, revising promotions or markdowns, improving supplier reliability, repairing master data, and resetting safety stock by service target and lead-time variability. Preserve a baseline and guardrails so a lower DIO does not merely shift cost or risk.
行动必须以诊断为基础，可能包括纠正预测偏差、降低最小起订量、改变订货频率、精简慢动 SKU、调整促销或降价、提高供应商可靠性、修复主数据，以及依据服务目标和交期波动重设安全库存。应保留基线和护栏，避免 DIO 下降只是转移成本或风险。
Frequently asked questions about days inventory outstanding关于存货周转天数的常见问题
What is the days inventory outstanding formula?存货周转天数公式是什么？
DIO equals average inventory divided by COGS for the same period, multiplied by the number of days in that period.
DIO 等于平均库存除以同一期间的销售成本，再乘以该期间天数。
Is a lower DIO always better?DIO 越低越好吗？
No. Lower DIO can mean faster movement and less cash tied up, but it can also result from understocking, stockouts, lost sales, or costly emergency replenishment.
不一定。较低 DIO 可能意味着周转更快、资金占用更少，也可能来自库存不足、缺货、销售损失或高成本紧急补货。
What is the difference between DIO and inventory turnover?DIO 与库存周转率有什么区别？
They express the same cost-based relationship in different units. Turnover reports cycles per period; DIO reports approximate days. DIO equals period days divided by turnover.
两者用不同单位表达同一个成本关系。周转率报告期间内的周转次数，DIO 报告估算天数；DIO 等于期间天数除以周转率。
Can DIO be calculated monthly or quarterly?DIO 可以按月或按季度计算吗？
Yes. Match inventory and COGS to the same period and multiply by its actual days. Use periodic inventory snapshots when endpoints do not represent the period.
可以。库存与销售成本必须对应同一期间，并乘以实际期间天数；如果端点缺乏代表性，应使用周期库存快照。
Does DIO show the actual age of every inventory item?DIO 能显示每件库存的实际库龄吗？
No. DIO is an aggregate financial estimate. Use receipt, lot, expiry, and last-movement timestamps for item-level aging.
不能。DIO 是汇总财务估计；单品库龄应使用收货、批次、到期和最后移动时间戳。
Sources, accounting boundaries, and verification资料来源、会计边界与核验说明
The DIO formula, inventory turnover relationship, and cash conversion cycle framing were checked against the NYU Stern ratio-analysis overview. Inventory cost, recognition, write-down, and disclosure boundaries should follow the entity's applicable accounting framework; see the official IFRS Foundation summary of IAS 2 Inventories.
DIO 公式、与库存周转率的关系及现金转换周期框架，参考了纽约大学 Stern 比率分析资料。库存成本、确认、减值与披露边界应遵循企业适用的会计框架；可参阅 IFRS Foundation 官方的 IAS 2 存货准则摘要。
This page provides an analytical workflow, not accounting, audit, investment, tax, or procurement advice. Definitions vary by data model, accounting policy, business model, and jurisdiction. Version the metric, reconcile it to controlled reports, and have qualified owners approve decisions. For monitoring principles after calculation, see the InfiniSynapse guide to a focused data dashboard.
本页提供分析工作流，不构成会计、审计、投资、税务或采购建议。定义会因数据模型、会计政策、商业模式和司法辖区而异。请对指标进行版本管理，与受控报表核对，并由合格责任人批准决策。完成计算后，可参考 InfiniSynapse 的聚焦型数据仪表板指南了解监控原则。