The inventory turnover calculator shows how many times a year your stock sells through — and how many days the average item sits on the shelf. Slow turns quietly tie up cash that could be working elsewhere.
The formula
Turnover = Annual COGS ÷ Average inventory, and Days inventory outstanding (DIO) = 365 ÷ Turnover. COGS is used rather than revenue because inventory is carried at cost — mixing in the sales markup would flatter the number.
Worked example
Annual COGS of $1.2M against average inventory of $200K: turnover = 6×, so DIO = 365 ÷ 6 ≈ 61 days. Stock sits for two months on average. Cutting average inventory to $150K (turns to 8×) frees $50K of cash permanently — that’s the point of watching this ratio.
How to read the result
Benchmarks differ hugely: grocery turns 12-20× a year, apparel 4-6×, furniture 2-4×. Higher is generally better — until stockouts start costing sales, which is the honest trade-off. A falling turnover trend is the early warning of dead stock and markdowns ahead. Pair with the margin calculator: high-margin slow movers can still beat low-margin fast movers.
What is a good inventory turnover ratio?
Depends on the category: grocery 12-20×, general retail 6-12×, apparel 4-6×, big-ticket goods 2-4×. Compare against your own sector.
Why use COGS instead of sales?
Inventory is valued at cost. Dividing sales (which include markup) by cost-valued inventory inflates the ratio artificially.
How do I calculate average inventory?
(Beginning inventory + ending inventory) ÷ 2 for the period — or average the month-end figures for a smoother number in seasonal businesses.
Can turnover be too high?
Yes — extremely high turns can signal chronic understocking and lost sales. The goal is fast turns without stockouts on your best sellers.