Inventory Turnover Ratio: Formula & Ecommerce Benchmarks
Inventory turnover tells you how many times your stock cycles through per year. Too slow and your cash is trapped. Too fast and you're stockout-prone.
Jakob Sperber
Director
Finance
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Inventory turnover ratio tells you how many times you sell and replace your stock in a given period. It's the speed at which cash moves through your product — fast turnover means cash cycles quickly, slow turnover means cash is trapped in boxes.
The Formula
Inventory Turnover Ratio = Cost of Goods Sold / Average Inventory
Use COGS (not revenue) in the numerator. Average Inventory = (Opening + Closing) / 2.
Worked Example
Annual COGS: $480,000. Opening inventory: $100,000. Closing: $80,000. Average inventory: $90,000.
ITR = $480,000 / $90,000 = 5.3x. You turned your inventory 5.3 times in the year.
ITR vs Days Inventory Outstanding
They're inverses. DIO = 365 / ITR. An ITR of 5.3 = DIO of 69 days. Both measure the same thing from different angles.
Benchmarks by Category
Consumables (supplements, food, skincare): 8–12x (30–45 days DIO)
Fashion/apparel: 4–6x (60–90 days DIO)
Beauty: 6–10x (36–60 days DIO)
Home goods: 2–4x (90–180 days DIO)
Electronics: 6–8x (45–60 days DIO)
Why It Matters
High turnover = cash cycling fast = more money available for marketing, operations, and growth. Low turnover = cash trapped in stock = constrained growth.
Two brands at $1M revenue: one with 8x turnover holds ~$125k in inventory. One at 3x holds ~$333k. The second brand has $208k more locked in stock — cash that can't fund ads or new products.
How Turnover Connects to Marketing Budget
Your ability to spend on acquisition is limited by available cash. If inventory is cycling slowly, your ad spend ceiling drops. Smart operators plan inventory and media spend together, tracking how turnover impacts their unit economics at each level.
How to Improve Inventory Turnover
1. Better Demand Forecasting
Use trailing 90-day sell-through rates by SKU, factoring in seasonality and planned marketing spend changes.
2. Reduce Dead Stock
Set a rule: if a SKU hasn't moved in 60 days, it hits clearance. Flash sale, bundle, B2B liquidation, or marketplace listing.
3. Smaller, More Frequent Orders
Switch from quarterly mega-POs to monthly orders. A 5% unit cost increase is worth it if turnover improves significantly.
4. Dropship Slow Movers
Long-tail SKUs with infrequent sales don't need warehouse space. Dropship or print-on-demand eliminates holding cost.
5. Review SKU Count
20% of SKUs drive 80% of revenue. Audit ruthlessly — fewer SKUs = deeper stock on winners = faster turnover.
Common Mistakes
Chasing high turnover by understocking. Leads to stockouts and lost revenue. Balance speed with availability.
Ignoring seasonal patterns. Pre-BFCM stock builds temporarily lower turnover. That's planned, not a problem.
Using revenue instead of COGS. Revenue inflates the ratio. Always use COGS for accuracy.
BFCM and Seasonal Planning
Turnover drops before major sales events as you build stock. The key: model the drop in advance, set aggressive sell-through targets during the event, and have a clearance plan ready for unsold inventory by mid-December. As covered in our ecommerce accounting guide, tracking these dynamics monthly prevents surprises.
The Bottom Line
Inventory turnover is the bridge between your product decisions and your cash position. Track it monthly. Benchmark against your category. Treat every improvement as cash freed up to deploy somewhere more productive.
