What is inventory turnover?

Inventory turnover measures how many times a business sells and replaces its entire inventory in a given period, typically a year. A turnover of 6× means you cycled through your average stock six times that year.

What is the inventory turnover formula?

Inventory Turnover = Cost of Goods Sold ÷ Average Inventory Value. For example: COGS of £600,000 and average inventory of £100,000 gives a turnover of 6×. To convert to Days Sales of Inventory: DSI = 365 ÷ Turnover = ~61 days.

What is a good inventory turnover ratio?

For most ecommerce brands, 6 – 8× per year is a healthy target. FMCG brands aim for 10 – 15×; fashion brands target 6 – 12×; electronics 4 – 8×; home goods 2.5 – 5×. Below 4× for a non-luxury brand almost always signals overstock.

Should I use COGS or sales revenue for inventory turnover?

Always use COGS (cost of goods sold) for an accurate, comparable result. Using revenue inflates the turnover ratio by your gross margin percentage and makes your numbers incomparable to industry benchmarks.

What does a low inventory turnover mean?

Low turnover means stock is selling slowly relative to how much you are holding. Common causes include over-buying, poor demand forecasting, end-of-season unsold stock, or products that have lost demand. Review your slowest-turning SKUs for markdown or discontinuation.

How do I calculate inventory turnover in Shopify?

Shopify does not have a built-in inventory turnover report. Pull annual COGS from Shopify Analytics (requires unit costs to be entered per product), calculate average inventory value from monthly end-of-period snapshots, then divide COGS by average inventory.

Inventory Turnover Calculator for Shopify | Free Formula + Benchmarks

Definition: Inventory turnover measures how many times a business sells and replaces its entire stock in a given period. A higher ratio means stock is moving faster and capital is being used efficiently.

Inventory turnover is one of the most useful single numbers in ecommerce operations. It tells you whether your buying decisions are translating into sales efficiently, whether you are over-stocked relative to your demand, and how much working capital is sitting idle on your warehouse shelves. Most Shopify brands do not know their turnover rate - and those that do often calculate it incorrectly by using revenue instead of cost of goods sold. This calculator gives you the right formula, the right benchmarks, and the practical context to act on the number.

Inventory Turnover Calculator formulas

COGS-based (recommended)

Use when: Always preferred. COGS-based turnover is a true measure of how quickly you sell through stock at the cost you paid for it. Enables fair cross-category and industry comparison.

Inventory Turnover = COGS / Average Inventory Value

Inventory Turnover = Cost of Goods Sold ÷ Average Inventory Value (at cost)

Symbol	Variable	Description
COGS	Cost of Goods Sold(£ / $)	The direct cost of inventory sold in the period. Found in your Profit & Loss statement. In Shopify, enter unit costs to get COGS from reports.
Avg Inventory	Average Inventory Value(£ / $)	Mean value of inventory held during the period, at cost. Calculate as (Opening inventory value + Closing inventory value) / 2. Using a 12-month average of monthly inventory values is more accurate.

Limitation: Requires accurate COGS data. Many Shopify merchants do not enter unit costs, making COGS reporting inaccurate.

Revenue-based (approximate)

Use when: Use when COGS data is not available. Produces a higher ratio than the COGS method because revenue includes your gross margin.

Inventory Turnover = Revenue / Average Inventory Value

Inventory Turnover = Net Revenue ÷ Average Inventory Value (at cost)

Symbol	Variable	Description
Revenue	Net revenue(£ / $)	Total sales net of returns and discounts. Easier to pull from Shopify than COGS.
Avg Inventory	Average Inventory Value(£ / $)	Mean inventory held at cost during the period.

Limitation: Not comparable to industry benchmarks, which are almost always COGS-based. Makes high-margin brands look more efficient than they are.

Days of Inventory Outstanding (DSI)

Use when: DSI is often more intuitive than the turnover ratio - it tells you how many days of sales your current inventory covers. A DSI of 60 means you have 60 days of stock on hand.

DSI = 365 / Inventory Turnover

Days Sales of Inventory = 365 ÷ Inventory Turnover Rate

Symbol	Variable	Description
365	Days in a year(days)	Use 30 for a monthly DSI, 90 for quarterly.
Inventory Turnover	Your calculated turnover rate(×)	From the COGS-based formula above.

Step-by-step examples

Scenario: “A Shopify fashion brand. Annual COGS: £600,000. Opening inventory value: £90,000. Closing inventory value: £110,000.”

Annual COGS: £600,000

Opening inventory (at cost): £90,000

Closing inventory (at cost): £110,000

1Average inventory = (£90,000 + £110,000) / 2 = £100,000
2Inventory turnover = COGS / Avg inventory = £600,000 / £100,000 = 6×
3DSI = 365 / 6 = ~61 days

Inventory turnover = 6× per year (DSI = 61 days)

Interpretation: This brand turns its stock 6 times per year, holding roughly 61 days of inventory at any time. For fashion, a target of 8 – 10× is strong; 6× is decent but suggests room to reduce average stock or improve sell-through.

Scenario: “A Shopify electronics brand. Annual COGS: £1,200,000. Monthly average inventory: £250,000.”

Annual COGS: £1,200,000

Average monthly inventory: £250,000

1Inventory turnover = £1,200,000 / £250,000 = 4.8×
2DSI = 365 / 4.8 = ~76 days

Inventory turnover = 4.8× (DSI ≈ 76 days)

Interpretation: Electronics benchmarks sit at 4 – 8× per year. At 4.8×, this brand is within range but toward the lower end - suggesting it could reduce stock levels or push through slower-moving SKUs more aggressively.

Industry inventory turnover benchmarks

Category	Benchmark	Note
Fast-moving consumer goods (FMCG)	10 – 15×	Very high velocity. Grocery, personal care, consumables.
Fashion and apparel	6 – 12×	Seasonal nature means turnover varies widely by quarter.
Electronics	4 – 8×	Rapid obsolescence makes high turnover desirable.
Home goods and furniture	2.5 – 5×	Larger, less frequent purchases lead to lower turnover.
Luxury / high-price items	2 – 4×	Deliberate buying patterns. Low turnover is acceptable.
General DTC ecommerce target	6 – 8×	Aim for at least 6× before investigating individual SKU performance.

Below 4× for a non-luxury brand almost always indicates overstock. Above 12× may signal under-stocking risk - check your fill rate and stockout frequency alongside turnover.

Critical pitfalls to avoid

Using revenue instead of COGS

Calculating turnover as Revenue / Inventory produces a higher number that is not comparable to industry benchmarks. A 60% gross margin brand appears to turn stock 2.5× faster than it actually does.

Fix: Always use COGS for the numerator. If you do not track COGS in Shopify, enter unit costs per product to enable accurate reporting.

Using ending inventory instead of average inventory

Taking stock value on December 31 as your 'inventory' for an annual calculation misrepresents your average holdings - especially if December is a low-stock month after peak sales.

Fix: Calculate average inventory from monthly snapshots: sum the 12 month-end inventory values and divide by 12.

Calculating a single turnover for the whole catalog

A business-wide turnover of 6× could hide a hero SKU turning 20× and a dead SKU turning 0.5×. The aggregate masks where the problem is.

Fix: Segment by product category (A/B/C or by collection in Shopify). Fix your slowest-moving categories first.

Including negative inventory in Shopify

Shopify allows negative inventory (oversells, bundle mismatches). Including negative stock values distorts average inventory and inflates the apparent turnover rate.

Fix: Clean up negative inventory values in your data before calculating. Set inventory policies to prevent overselling where possible.

Not accounting for seasonality

A brand with a big Q4 peak will show a very high turnover in that quarter and low turnover in Q1 – Q3. Annual averages can mask both over- and under-stocking issues.

Fix: Review turnover quarterly, not just annually. Compare Q4 this year to Q4 last year, not to Q1 this year.

Shopify-specific tips

Shopify does not display inventory turnover natively. Pull COGS from Shopify Analytics (requires cost per item to be set on each product variant) and inventory value from the Inventory by location report.
To get average monthly inventory, export 'Inventory at the end of month' reports for each month and calculate the mean.
If COGS is unavailable in Shopify, use Net Sales × (1 − gross margin %) as an approximation - but note this is less accurate.
Use Shopify collections or product tags to segment turnover by category. This is far more actionable than a store-wide average.
Shopify's built-in ABC analysis (available on some plans) groups products by revenue contribution - use this alongside turnover data to identify slow-movers in your A-tier.

Inventory Turnover Calculator