TL;DR
DIO (Days Inventory Outstanding) measures how many days of inventory a company holds before selling it. For D2C brands, 30–60 days is healthy; above 90 is a cash-flow and obsolescence risk. A 15-day reduction in DIO on $200K of monthly COGS frees roughly $100K in working capital.
What is DIO?
Days Inventory Outstanding (DIO, also called days inventory held, inventory days, or days in inventory) measures the average number of days a company holds inventory before it is sold. It is the inventory leg of the cash conversion cycle: CCC = DSO + DIO − DPO.
DIO is primarily relevant for D2C brands, e-commerce companies, and any business holding physical inventory. For pure-play B2B SaaS with no physical component, DIO is effectively zero — software doesn't sit in a warehouse.
The tradeoff in DIO is between holding enough inventory to prevent stockouts (which cost revenue and customer satisfaction) and holding so much that cash is trapped in slow-moving stock. Getting this balance right is a fundamental operating discipline for product businesses.
Why DIO matters for operators
High DIO is expensive in two ways: the cash cost of holding the inventory and the risk that some of it becomes obsolete or requires markdown. A D2C brand with $300K of average inventory and DIO of 85 days has over $80K more cash tied up than a competitor with a 45-day DIO — on the same revenue base.
DIO also signals demand forecasting accuracy. A sudden spike in DIO — inventory growing while revenue holds flat — usually means a demand shortfall or a forecasting error. Catching it early, when inventory is still current, allows the operator to run a promotion or redirect stock. Catching it at 120 days DIO means markdowns, obsolescence write-offs, or both.
For D2C brands using Shopify and running paid acquisition, DIO and inventory turnover directly affect whether you can reinvest ad spend in the next cycle. Cash tied up in unsold inventory can't fund the next media buy.
DIO formula
DIO = (Average Inventory / COGS) × Days in Period Example (quarter): Beginning inventory (Q2): $280,000 Ending inventory (Q2): $320,000 Average inventory: ($280,000 + $320,000) / 2 = $300,000 COGS in Q2: $480,000 Days in Q2: 91 DIO = ($300,000 / $480,000) × 91 = 56.9 days Simplified (point-in-time): DIO = (Ending Inventory / COGS) × Days in Period — faster to calculate; use for operational monitoring
DIO benchmarks by category
| Category | Healthy DIO | Warning zone | Critical | Primary risk |
|---|---|---|---|---|
| Fashion / apparel (D2C) | 30–60 days | 60–90 days | >90 days | Seasonality, style obsolescence |
| Beauty / CPG (D2C) | 45–75 days | 75–100 days | >100 days | Shelf life, ingredient expiry |
| Consumer electronics (D2C) | 20–45 days | 45–60 days | >60 days | Technology obsolescence |
| Consumables / supplements | 30–60 days | 60–90 days | >90 days | Expiry dates, regulatory |
| Home goods / décor | 45–90 days | 90–120 days | >120 days | Trend cycles, storage cost |
| B2B SaaS (no inventory) | 0 days | N/A | N/A | N/A — metric not applicable |
Sources: Shopify Commerce Trends 2025; Common Thread Collective D2C Benchmarks 2025; Fairview customer data.
Common mistakes when tracking DIO
1. Using ending inventory instead of average inventory. If your business has seasonal peaks, point-in-time inventory can be highly misleading. Use the average of beginning and ending inventory for the period — or a rolling monthly average for more accuracy.
2. Tracking DIO at the company level but not by SKU. A healthy 50-day blended DIO can hide one SKU at 120 days and two SKUs at 20 days. SKU-level DIO is where the actual operational decisions live — which SKUs to reorder, which to promote, which to discount or discontinue.
3. Ignoring in-transit inventory. Goods ordered from a supplier and on the water are not yet in your warehouse but are committed cash. Include in-transit inventory in DIO tracking for an accurate picture of total capital at risk.
4. Not connecting DIO to cash planning. DIO is a cash metric, not just a supply-chain metric. Every incremental day of DIO is cash sitting on a shelf. Finance teams that track DIO in isolation from the cash conversion cycle miss its direct impact on runway and payables capacity.
5. Treating DIO as a procurement metric only. Reducing DIO requires coordination between procurement (buy less), marketing (sell faster via promotions), and product (discontinue low-velocity SKUs). Operators who assign DIO ownership solely to procurement rarely achieve sustained improvement.
How Fairview tracks DIO automatically
Fairview's Operating Dashboard connects Shopify and your accounting system (QuickBooks, Xero) to calculate DIO by SKU and in aggregate — refreshed weekly alongside DSO, DPO, and the full cash conversion cycle.
The Next-Best Action Engine flags inventory risk before it becomes a write-off: "Three SKUs have crossed 85-day DIO this week. Combined at-risk inventory value: $47,000. Recommended action: run a targeted promotion on these SKUs before the next intake to clear current stock."
Companies using Fairview typically identify 2–3 slow-moving SKU clusters within the first 30 days, enabling promotional decisions that prevent $30K–$100K of markdown exposure.
→ See how the Operating Dashboard tracks inventory and cash metrics
At a glance
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Frequently asked questions
What is a good DIO?
Depends heavily on product category. Fashion D2C: 30–60 days is healthy. Beauty/CPG: 45–75 days. Consumer electronics: 20–45 days. As a general rule, lower DIO frees cash, but too low risks stockouts that cost revenue. The right target is the minimum DIO that still meets your fill-rate requirement.
Is lower DIO always better?
Not always. DIO that's too low means you're running out of inventory before demand is met — stockouts cost more than the interest on the cash you'd have freed. The optimal DIO balances cash efficiency with service level. For most D2C brands, a fill rate target of 95%+ should be the constraint, with DIO minimized within that constraint.
What is the difference between DIO and inventory turnover?
Inventory turnover = COGS / Average Inventory. DIO = 1 / Inventory Turnover × Days in Period. They measure the same thing from different angles. Inventory turnover of 6x annually = DIO of ~61 days. Use whichever your team finds more intuitive. DIO is easier to benchmark against a cash target; turnover is easier to benchmark against industry multiples.
How do you reduce DIO?
Four levers: improve demand forecasting accuracy (order less, more frequently), run targeted promotions on slow-moving SKUs before they age further, negotiate shorter lead times with suppliers (reduces the buffer stock you need to carry), and discontinue SKUs with chronically high DIO.
Does DIO apply to B2B SaaS?
Rarely. Software doesn't sit in a warehouse. The exception is SaaS companies that ship physical hardware (onboarding kits, branded devices, IoT sensors) as part of their product. For those companies, hardware DIO is a real operating metric. For pure-software SaaS, the metric is not applicable.
Sources
- Shopify Commerce Trends 2025
- Common Thread Collective D2C Benchmarks 2025
- Mosaic FP&A Benchmarks 2025
- Klaviyo Benchmark Report 2025
- Fairview customer data (D2C brands, 2025)
Fairview is an operating intelligence platform that tracks DIO by SKU automatically — alerting you to slow-moving inventory before it ages into a markdown. Start your free trial →
Siddharth Gangal is the founder of Fairview. He built inventory-day tracking into the platform after watching D2C operators discover $50K+ of slow-moving stock at the end of a season that SKU-level DIO alerts would have surfaced six weeks earlier.
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