BusCalcTools

Inventory Turnover Calculator — Ratio & Days in Inventory

Last reviewed:

Calculate how many times per year you turn your inventory and how long average stock sits on the shelf — with industry-benchmark comparison.

Inventory turnover equals cost of goods sold divided by average inventory. Days in inventory equals three sixty-five divided by turnover.

How it works

Inventory turnover = Cost of Goods Sold ÷ Average Inventory. Average inventory is (beginning + ending) / 2. The ratio tells you how many times per year you completely cycle through your stock. Days in inventory = 365 ÷ turnover — the average number of days a unit sits before being sold.

Low turnover ties up cash, raises holding costs (insurance, warehousing, obsolescence), and risks markdowns. Very high turnover risks stockouts and lost sales. The right number depends on industry: grocery (15-30), apparel retail (4-8), automotive dealers (8-12), heavy machinery (1-3), B2B services or capital goods (1-2). Track yours over time as a leading indicator of operational efficiency.

Common mistakes

  • Using revenue instead of COGS. Some old textbooks use Revenue / Inventory — this overstates turnover by the gross margin percentage. Modern accounting practice is COGS / Inventory; use this.
  • Single-snapshot inventory. Using just the year-end inventory figure (instead of averaging begin + end) distorts seasonal businesses. For a more accurate read, use the average of 12 monthly inventory snapshots — most ERPs export this.
  • Treating high turnover as automatically good. A 50× turnover in a non-perishable goods business may signal chronic stockouts and lost revenue. The right turnover is the one that minimises stockouts AND markdowns simultaneously — usually 6-15 for retail, 5-10 for manufacturing.
See the formula
Turnover Ratio = Annual COGS / Average Inventory
  Average Inventory = (Beginning + Ending) / 2

Days in Inventory = 365 / Turnover Ratio

Industry Benchmarks (rough medians):
  Grocery / FMCG:           15-30×
  Apparel retail:            4-8×
  Specialty retail:          3-6×
  Restaurants:              30-100× (food spoilage forces fast turns)
  Auto dealers:              8-12×
  Manufacturing:             5-10×
  Heavy machinery / B2B:     1-3×
  Capital goods:             0.5-1.5×

Example: COGS $600,000 | Begin $120k, End $100k
  Avg Inventory  = $110,000
  Turnover       = $600,000 / $110,000 = 5.45× per year
  Days           = 365 / 5.45 ≈ 67 days

Worked example

A specialty retailer has $600,000 of COGS, $120,000 beginning inventory, $100,000 ending inventory. Average = $110,000. Turnover = 600 / 110 = 5.45×/year. Days in inventory = 365 / 5.45 = 67 days. Versus specialty-retail benchmark of 3-6×, this is healthy.

What if the same business had $200,000 of inventory instead? Average = $160k, turnover drops to 3.75×, days rise to 97. Same COGS, but the extra $50k tied up in inventory generates carrying costs (insurance, warehousing, capital cost) of typically 15-25% per year — or $7,500-$12,500. Cutting inventory back to $110,000 frees that cash AND reduces carrying costs.

The flip side: cutting too aggressively risks stockouts. A retailer with 9× turnover (40 days) may be losing 5-10% of sales to out-of-stock incidents. The right level is the one that minimises the SUM of holding costs and lost-sales costs — usually 6-8× for specialty retail.

When to use this calculator

Use this when you stock physical inventory and want to see whether you are turning it efficiently relative to your sector — retail, wholesale, light manufacturing, or distribution. It is also the right tool when planning a buying cycle, evaluating a slow-moving SKU, or building the working-capital section of a credit application.

If you sell services rather than goods, inventory turnover is not a relevant metric — switch to the Working Capital Calculator or the Cash Flow Calculator. For a deeper dive into how slow inventory ties up cash, pair this with the Working Capital Calculator to see the cash-conversion-cycle picture.

Frequently Asked Questions

What is inventory turnover?
A measure of how many times per year a business completely cycles through its inventory. Calculated as Annual COGS divided by Average Inventory. Higher turnover usually indicates more efficient inventory management, but can also signal stockout problems.
What is a good inventory turnover ratio?
Depends entirely on industry. Grocery 15-30 (perishables force fast turns). General retail 4-12. Specialty retail 3-6. Restaurants 30-100 (food spoilage). Auto dealers 8-12. Manufacturing 5-10. Heavy machinery 1-3. Capital goods 0.5-1.5. Compare to your own industry, not absolute thresholds.
What does days in inventory mean?
The average number of days a unit of inventory sits before being sold. Calculated as 365 / Inventory Turnover Ratio. Higher days = slower-moving inventory = more cash tied up in stock.
Why does inventory turnover matter?
Three reasons. (1) Cash flow — slow turnover ties up working capital. (2) Holding costs — insurance, warehousing, capital, and obsolescence run 15-25% of inventory value per year. (3) Markdown risk — slow inventory often gets marked down 25-50% to clear, destroying margin.
How do I improve inventory turnover?
Three levers. (1) Reduce inventory levels via just-in-time ordering, vendor-managed inventory, or smaller minimum order quantities. (2) Liquidate slow movers via clearance, B2B liquidation channels, or bundling with fast movers. (3) Improve demand forecasting to avoid over-buying in the first place. Most retailers can improve turnover 20-30% in 12 months through forecast and ordering discipline.
Can inventory turnover be too high?
Yes. Very high turnover often indicates frequent stockouts — lost sales because product isn't available when customers want it. A retailer with 20× turnover in a non-perishable category may be losing 10-15% of potential sales to out-of-stock incidents. The optimal turnover balances holding costs against stockout costs.
Should I use revenue or COGS in the formula?
COGS, not revenue. Some older textbooks use Revenue / Inventory but this overstates turnover by the gross margin percentage. Modern accounting practice and all comparable industry benchmarks use COGS / Inventory. Mixing the two makes cross-company comparisons meaningless.
What is the inventory days outstanding (DIO)?
Same as 'days in inventory' — 365 / Turnover. Together with DSO (days sales outstanding, on receivables) and DPO (days payable outstanding, on payables), it forms the cash conversion cycle: DSO + DIO − DPO. The lower the cycle, the less working capital your business consumes per dollar of revenue.
Does inventory turnover vary by season?
Yes substantially in seasonal businesses. Retailers might see turnover of 1-2 in January (post-holiday clearance) and 8-10 in December (peak holiday). Use an annual figure with 12-month average inventory for the headline number, then monitor a 3-month rolling figure to detect trends.
How does inventory turnover affect business valuation?
Acquirers and lenders use turnover to assess working-capital efficiency. A business with 8× turnover in a category where the median is 5× often commands a higher multiple — it's generating the same revenue with less capital tied up. The difference can be 10-25% of business value at sale.

Glossary

Turnover Ratio
Annual cost of goods sold divided by average inventory. How many times you completely cycle through stock in a year.
Days in Inventory
365 divided by the turnover ratio. The average number of days a unit sits on the shelf before being sold.
Carrying Cost
The annual cost of holding inventory — insurance, warehousing, capital cost, obsolescence, shrinkage. Typically fifteen to twenty-five percent of average inventory value.

Related calculators

Working Capital Calculator

Current ratio and bank-readiness from short-term assets and liabilities.

Open →

DSO Calculator

Days Sales Outstanding and the cash released by faster collections.

Open →

Cash Flow Calculator

Project 12-month cash flow from income and expenses.

Open →

Methodology & sources

Rates last verified: May 2026

Read the full methodology →

Uses (Beginning + Ending) / 2 for average inventory — the standard formula but inaccurate for highly seasonal businesses. For seasonal operations, average 12 monthly inventory snapshots instead. Industry benchmarks reflect approximate medians and vary by business model within each category (e.g. fast-fashion retail turns 15-25× while traditional apparel retail turns 4-8×).

Rates are reviewed annually or when a region changes its headline rate. If you spot one that's out of date, email [email protected].

For information only. This calculator does not constitute financial, accounting, or tax advice. Consult a qualified professional before making business decisions.

Try these scenarios

Pre-filled examples — click any chip to load the inputs and result.

How to calculate inventory turnover

  1. Enter annual COGSCost of goods sold for the year — from your P&L.
  2. Enter beginning and ending inventoryInventory values at the start and end of the period — from balance sheets.
  3. Read the ratio and daysCompare against the industry benchmark shown in the third result card.

Found this calculator useful?

Save it to a Pinterest board for later, or share with your team.

Save to Pinterest
JB

Written by

James Blanckenberg

Founder, BusCalcTools

Founder of BusCalcTools and FinnCalc. Builds practical financial calculators for small business owners and freelancers across the US, UK, and South Africa.

Editorial review by: James Blanckenberg, Founder & Editor

More about James →

One short email a month

New calculators, pricing tactics, and small-business numbers worth knowing. No spam, unsubscribe in one click.