Inventory Turnover Calculator
Calculate inventory turnover ratio and days sales of inventory from annual COGS and beginning/ending inventory values. Standard retail and wholesale metric.
COGS, not revenue. Turnover measures inventory movement at cost basis.
For seasonal businesses, use a twelve-month average of month-end inventory values instead of the two-point calculation. The tool accepts whichever you provide.
About this tool
Inventory turnover measures how many times a business sells through its average inventory during a period. A higher turnover means inventory moves faster, tying up less working capital and exposing the business to less risk of obsolescence. A lower turnover means stock sits longer, which might mean overordering, demand shifts, or slow-selling categories that need markdown or discontinuation.
This calculator takes annual cost of goods sold and the inventory value at the beginning and end of the period. It computes the inventory turnover ratio (COGS divided by average inventory) and days sales of inventory (365 divided by turnover, showing how many days the average item sits in inventory before being sold).
Turnover varies widely by industry: grocery and quick-service consumables turn over many times per year, apparel retail turns over a few times, furniture and specialty goods turn over a handful of times across the whole year. What matters more than the absolute number is your own trend and the comparable for your specific category, because category mix and purchasing terms drive the baseline. See the break-even analysis calculator for a related working-capital discipline on the fixed-cost side.
How it works
Average inventory = (beginning_inventory + ending_inventory) / 2. For more accuracy when inventory has seasonal swings, use a twelve-month simple average of month-end values instead. The two-point calculation is the standard for quarterly and annual reporting.
Inventory turnover = annual_COGS / average_inventory. Also called the inventory turns ratio. A turnover of 6 means the business sold through 6× its average inventory during the year. COGS (not revenue) is the correct numerator because turnover measures the cost-basis movement of inventory through the business, not the retail-price revenue.
Days sales of inventory = 365 / turnover. Also called days inventory outstanding (DIO). A turnover of 6× per year equals 61 days on hand; the average item sits in inventory 61 days before selling. High-turnover businesses (grocery, perishables) aim for 30 days or fewer. Slow-turnover businesses (furniture, specialty) may sit at 90-180 days by design.
Inventory turnover is part of the cash conversion cycle (days inventory + days receivable - days payable). For a deeper working capital view, pair this calculation with separate days receivable and days payable analyses, which are not part of this tool.
Examples
A business turning over inventory about 4-5 times per year with 82 days on hand. Typical for specialty retail or apparel where seasonal buys need months to sell through.
High turnover around 11× per year, 33 days on hand. Characteristic of grocery, quick-service restaurants, or fast-moving consumer goods where inventory moves quickly and margin per unit is tight.
Slow turnover near 1× per year, over 300 days on hand. This is either a heavy-specialty retail model (high-end jewelry, antiques) where long hold is intentional, or a problem case where inventory is growing faster than sales. Investigate whether categories are obsolescing.
When to use
Use this quarterly to track whether inventory is accelerating or slowing against sales, when entering a new product category to benchmark expected turns, or when a lender or investor asks for working-capital ratios. Slow turnover ties up cash that could be reinvested elsewhere; very fast turnover may indicate understocking that leads to lost sales. Pair with the profit margin calculator for the profitability side and the cash burn runway calculator to see how inventory cash is affecting overall runway.
Related concepts
Frequently asked questions
Should I use beginning and ending inventory or a monthly average?
Use a monthly average if your inventory fluctuates seasonally. A retailer with Q4-heavy sales will have a very different inventory balance in December vs. January. Two-point calculation understates turnover in a seasonal business. Twelve monthly endings averaged gives a cleaner number.
Why COGS instead of revenue?
Turnover measures how inventory moves through the business at cost basis, not at retail price. Using revenue as the numerator would inflate the turnover number and make it non-comparable across businesses with different markups.
What about manufacturing inventory?
The same formula works but typically with separate turnover ratios for raw materials, work in progress, and finished goods. Most small businesses conflate these; larger manufacturers compute each separately because the management decisions differ.
Sources
- IRS Publication 538 (Accounting Periods and Methods)
(primary, accessed Apr 16, 2026)
Federal tax guidance on inventory valuation methods (FIFO, LIFO, weighted average) that determine the COGS figure used in turnover calculations.
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