Days Sales of Inventory (DSI) Calculator

Free Days Sales of Inventory (DSI) calculator. Enter average inventory and cost of goods sold to find how many days it takes to sell through stock.

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Days Sales of Inventory (DSI) Calculator

Find how many days, on average, it takes to sell through your inventory. No signup required.

By Tibeau De Grauwe, FounderUpdated September 2026

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Days Sales of Inventory (DSI), sometimes called Days Inventory Outstanding (DIO), measures how many days it takes, on average, to sell through the inventory you're holding. It's a cash-flow-oriented way of looking at the same underlying efficiency that inventory turnover measures.

DSI Calculator

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Days Sales of Inventory

60.8 days

Equivalent to 6.0x inventory turnover per period

The DSI formula

DSI = (Average Inventory ÷ Cost of Goods Sold) × Number of Days in the Period. Average inventory is typically (beginning inventory value + ending inventory value) ÷ 2 for the period; COGS is the direct cost of inventory sold during that same period.

Example: a business carries $40,000 in average inventory and has $240,000 in annual COGS. DSI = (40,000 ÷ 240,000) × 365 ≈ 61 days — it takes roughly two months, on average, to sell through the stock on hand.

DSI and inventory turnover are the inverse of each other (turnover = 365 ÷ DSI, and vice versa). Neither is universally "better" to track — DSI is more intuitive for cash-flow conversations ("how many days of cash is tied up"), turnover is more common for comparing efficiency across periods or SKUs.

See also: the DSI glossary entry, the inventory turnover calculator, the inventory turnover guide.

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Frequently asked questions

What is the DSI formula?
Days Sales of Inventory = (Average Inventory ÷ Cost of Goods Sold) × Number of Days in the Period, most commonly calculated annually with 365 days. It measures how many days, on average, it takes to sell through inventory.
What is a good DSI?
It depends heavily on industry and business model — a grocery retailer might target single-digit DSI for perishables, while a furniture retailer might reasonably run 60-90+ days. Compare DSI against your own historical trend and close competitors rather than a universal benchmark.
Is a lower DSI always better?
Generally lower DSI means faster cash conversion and less capital tied up, but extremely low DSI can also signal you're running too lean and risking stockouts. The right DSI balances cash efficiency against your actual stockout risk and lead times.
How is DSI different from inventory turnover?
They describe the same underlying efficiency from different angles: turnover (COGS ÷ Average Inventory) tells you how many times inventory is sold and replaced in a period, while DSI tells you the average number of days that takes. They are mathematically the inverse of each other.