How is inventory turnover calculated?

Inventory turnover = cost of goods sold ÷ average inventory. It tells you how many times stock is sold and replaced over the period.

What are days inventory outstanding?

Days inventory outstanding ≈ 365 ÷ turnover. It estimates how many days, on average, stock sits before being sold.

What is a good inventory turnover ratio?

It varies by industry. Grocery and fast-fashion retailers often turn 8-15 times a year, while furniture or jewellery may turn 2-4 times. Compare against peers in your sector rather than a single universal benchmark.

Should I use sales or COGS in the formula?

Use cost of goods sold, not sales revenue. COGS and inventory are both valued at cost, so the ratio is consistent. Using sales revenue overstates turnover because it includes your profit margin.

How do I find average inventory?

The simplest method is (opening inventory + closing inventory) ÷ 2 for the period. For seasonal businesses, averaging monthly balances gives a more accurate figure.

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What is the Inventory Turnover Calculator?

Free inventory turnover ratio calculator. Enter cost of goods sold and average inventory to get turnover times per year and days inventory outstanding. Runs entirely in your browser — nothing is uploaded. It runs free in your browser on Gera Tools, with nothing uploaded.

Inventory Turnover Calculator

Name: Inventory Turnover Calculator
Creator: Gera Tools
License: https://creativecommons.org/licenses/by/4.0/

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Inventory turnover calculator

Inventory turnover measures how efficiently a business sells through its stock. It is a key metric for retailers, wholesalers and manufacturers because it reveals whether capital is tied up in slow-moving inventory or working hard. This calculator returns both the turnover ratio and days inventory outstanding.

How it works

The calculator uses two standard formulas:

Inventory turnover = cost of goods sold ÷ average inventory — how many times stock is sold and replaced over the period.
Days inventory outstanding (DIO) = 365 ÷ turnover — the average number of days a unit sits before it sells.

A higher turnover (and lower DIO) means stock moves quickly; a low ratio can signal overstocking, weak demand or obsolete goods.

Example

A shop with $500,000 annual COGS and $100,000 average inventory:

Turnover = 500,000 ÷ 100,000 = 5 times per year
DIO = 365 ÷ 5 = 73 days

So on average the shop sells through its entire inventory five times a year, with stock sitting about 73 days before sale.

What the ratio tells you — and what it hides

A high turnover ratio looks healthy, but context matters in both directions:

Too high can be a problem. A turnover so high that stockouts are frequent means you are losing sales you could have made. Retailers call this a service level issue: customers arrive wanting a product that is perpetually out of stock, and eventually they go elsewhere. If your DIO is in single digits, ask whether you are running out of popular items.

Too low ties up cash. Inventory sitting for 180+ days represents cash that is not circulating. It also carries hidden costs — warehousing, obsolescence risk, insurance, and the opportunity cost of the capital. Slow-moving inventory is one of the most common ways small businesses quietly run out of working capital.

Industry context is essential. A grocery retailer might turn inventory 20–25 times per year because food is perishable and demanded daily. A jeweller or furniture retailer might turn 2–4 times and be entirely healthy for their sector. Compare your ratio against your own history and your peer group, not a universal “good” number.

How to calculate average inventory correctly

The simplest method is: (opening inventory + closing inventory) ÷ 2 for the period. This works well for businesses with relatively stable stock levels. For seasonal businesses — retail peaks in November-December, garden centres in spring — averaging only start and end balances can be misleading because the peak is invisible. In that case, average monthly closing balances across all 12 months gives a more accurate figure.

Connecting turnover to cash flow

Inventory turnover is one component of the cash conversion cycle (CCC): the number of days from paying for inventory to collecting cash from customers. A shorter CCC means less cash tied up in operations. Reducing DIO by 10 days on a business with $1M of inventory and 10 turns frees roughly $27,000 of working capital — small improvements compound meaningfully at scale.

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