Free Inventory Turnover Calculator
Measure inventory turnover and days on hand with period and annualized results using inventory valued at cost. Use advanced options and copy or download your results. Browser-based and no signup required.
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How to use the inventory turnover calculator
Measure inventory turnover and days on hand with period and annualized results using inventory valued at cost. No signup required.
- Enter the period cost of goods sold and the number of calendar days in that period.
- Choose opening/closing average inventory or enter a direct average calculated from more frequent inventory balances.
- Use inventory valued at cost, then compare period turnover, annualized turnover and days inventory outstanding.
- Adjust the period inputs to compare scenarios and copy or download the inputs and results.
Who benefits from tracking inventory turnover
Inventory turnover tells you how many times your stock was sold through and replaced during a period. Retailers, online sellers, wholesalers and small manufacturers use it to spot cash tied up on shelves. A falling ratio can point to overbuying or slow-moving products. A very high ratio can mean lean stock, but it can also signal frequent stockouts.
The calculator is handy for monthly or quarterly reviews, for comparing product lines or warehouses, and for preparing questions before a meeting with an accountant or lender. It works with any period length from 1 to 3,660 days, so you can measure a single month, a quarter, a season or a full year.
A worked example for one quarter
Say a shop had cost of goods sold of 45,000 over a 90-day quarter. Inventory at cost was 18,000 at the start and 12,000 at the end. With the opening and closing method, average inventory is (18,000 + 12,000) / 2 = 15,000.
Period turnover is 45,000 / 15,000 = 3.00 times. Annualized turnover is 3.00 x 365 / 90 = 12.17 times. Days inventory outstanding is 15,000 / 45,000 x 90 = 30.00 days, meaning the average unit sat in stock for about a month before it sold.
If you track monthly balances instead, choose the direct average option. For example, month-end balances of 18,000, 14,000, 16,000 and 12,000 average 15,000, which happens to match here. In a seasonal business the two methods can differ a lot.
Expressed another way, this shop turned over its stock about once a month during the quarter. If the next quarter shows 45 days on hand with similar sales, cash is sitting in inventory for longer.
How the formulas fit together
The calculator uses three standard relationships. Turnover equals period COGS divided by average inventory at cost. Annualized turnover equals period turnover multiplied by 365 and divided by the number of days in the period. Days inventory outstanding equals average inventory divided by COGS, multiplied by the period days.
Turnover and days outstanding are two views of the same idea. For a 365-day period, 365 divided by turnover gives the same days figure. A higher turnover means fewer days on hand, and the reverse. Results show as undefined when a value would require dividing by zero, such as zero average inventory or zero COGS for the days figure.
Common mistakes to avoid
Do not mix periods. COGS for a quarter must be paired with a 90-day or similar period and with balances from that same quarter. Do not use sales revenue in place of COGS, because revenue includes your markup and inflates the ratio.
Be careful with benchmarks. A healthy ratio for a grocery store is very different from one for a furniture store or a parts supplier. Compare yourself mainly with your own history and with businesses in the same category, and talk to an accountant before making major purchasing or financing decisions from these figures.
Useful tips and limitations
- Do not substitute sales revenue for cost of goods sold.
- Seasonal stores benefit from a direct average based on multiple balances rather than only two endpoints.
- Run the calculator separately for each product category, because one slow line can hide behind a healthy store-wide ratio.
- Use the Download CSV option each period so you can build a simple trend of turnover and days on hand over time.
Common questions
How is annualized inventory turnover calculated?
The period turnover is multiplied by 365 and divided by the period length in days. This is a simple annualization, not a forecast of future demand.
Why is inventory turnover undefined for zero average stock?
Turnover divides COGS by average inventory. A zero denominator has no finite turnover result, so the calculator displays an undefined value.
Should inventory turnover use retail prices or cost?
Use cost of goods sold and inventory valued at cost from the same period and accounting basis. Mixing retail values with cost values gives misleading results.
What is a good inventory turnover ratio?
There is no single good number. It depends on your industry, margins and supply lead times, so the most useful comparison is your own trend over time and peers selling similar products.
How do turnover and days inventory outstanding relate?
They are inverses scaled by the period length. Days inventory outstanding equals average inventory divided by COGS times the period days, so higher turnover always means fewer days on hand.
Does the currency selector convert my amounts?
No. It only changes how amounts are displayed. Enter COGS and inventory balances in the same currency.
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