Rex says
Money math without the spreadsheet headache. Plug in your numbers and I'll show you exactly where the dollars land.
Try a scenario
Click to load — tweak from there.Inputs
Result
Inventory turns per year
6.00
Days sales of inventory
60.8
Average inventory value
$700,000
Turns per month
0.50
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How to use this
- 1Enter annual cost of goods sold ($).
- 2Enter beginning inventory value ($).
- 3Enter ending inventory value ($).
- 4Read your inventory turns per year on the right — it updates as you type.
- 5Hit Share to keep the scenario or send it to someone.
About this calculator
Inventory turnover measures how many times you sell through your average inventory in a period, and days sales of inventory (DSI) converts that same relationship into how many days of supply you're carrying — the two are mathematical inverses of each other expressed differently. Higher turns and lower DSI generally mean better working capital efficiency, but the right number is category-dependent: grocery and fast fashion should turn 8-15+ times a year, while durable goods, spare parts, and slow-moving industrial inventory might reasonably turn 2-4 times. This calculator computes both metrics from cost of goods sold and average inventory value, and flags how your DSI compares to typical cash-conversion-cycle targets so you know whether working capital is tied up longer than it needs to be.
Worked example
Using the values the calculator loads with:
Inputs
- Annual cost of goods sold: 4200000 $
- Beginning inventory value: 680000 $
- Ending inventory value: 720000 $
Results
- Inventory turns per year: 6
- Days sales of inventory: 60.8
- Average inventory value: $700,000
- Turns per month: 0.5
What each field means
Inputs
- Annual cost of goods sold ($)
- The annual cost of goods sold used in the calculation, measured in $. Starts at 4200000 $ so you have a working example on load.
- Beginning inventory value ($)
- The beginning inventory value used in the calculation, measured in $. Starts at 680000 $ so you have a working example on load.
- Ending inventory value ($)
- The ending inventory value used in the calculation, measured in $. Starts at 720000 $ so you have a working example on load.
Results
- Inventory turns per year
- Returned as a decimal number and shown as the headline result. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Days sales of inventory
- Returned as a decimal number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Average inventory value
- Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Turns per month
- Returned as a decimal number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
FAQ
What's a healthy inventory turnover rate?
It's category-specific: grocery and perishables run 12-20+ turns a year, general retail and apparel 4-8, industrial/MRO parts 2-4, and spare parts for long-life equipment can reasonably run below 2. Compare your turns against your own industry peers, not a universal number, because a 3-turn rate is excellent for aircraft parts and terrible for fresh produce.
Why use average inventory instead of ending inventory?
Ending inventory can be a snapshot distorted by a recent large receipt or a stockout right at period close, either of which skews the ratio. Averaging beginning and ending balances smooths that noise; for highly seasonal businesses, an average of monthly ending balances across the year gives an even more accurate picture.
How does DSI relate to cash conversion cycle?
DSI is one of three components of the cash conversion cycle, along with days sales outstanding (how long customers take to pay) and days payable outstanding (how long you take to pay suppliers). Cash conversion cycle = DSI + DSO − DPO, and reducing DSI directly shortens the time cash is tied up before it comes back in from a sale.
What's the risk of pushing turns too high?
Chasing extremely high turnover by cutting inventory too aggressively increases stockout risk and can force expensive expedited replenishment or lost sales. There's a real trade-off between capital efficiency and service level — use the safety stock and reorder point calculators alongside this one to find inventory levels that support your service target without carrying excess.
Accuracy and limitations
- Results are estimates before tax, fees, and inflation unless an input explicitly covers them.
- Rates are treated as fixed for the whole period — variable-rate products will drift from this projection.
- This is educational maths, not financial advice. Check anything contractual with the lender or your accountant.
Related tools
Cite this calculator
Writing about this topic? Grab a citation — every link helps keep these tools free.
RevenueLab. (2026). Inventory Turns & Days Sales of Inventory Calculator. Retrieved from https://www.revenuelab.fyi/toolbox/inventory-turns-dsi
<p>Source: <a href="https://www.revenuelab.fyi/toolbox/inventory-turns-dsi" target="_blank" rel="noopener">Inventory Turns & Days Sales of Inventory Calculator — RevenueLab</a> (2026).</p>
Source: [Inventory Turns & Days Sales of Inventory Calculator — RevenueLab](https://www.revenuelab.fyi/toolbox/inventory-turns-dsi) (2026).