The inventory to sales ratio is the value of your stock at cost divided by your net sales for the same period. Measured against one month's sales, it tells you how many months of sales sit on your shelves. A ratio of 0.72 means stock worth about three weeks of selling.
It also goes by stock to sales ratio and I/S ratio. This guide works it for a Kampala minimarket in Uganda shillings. It shows why the period you choose changes the answer, and compares the result with the US Census Bureau's ratios by kind of store.
The formula and its three inputs
Inventory to sales ratio = average inventory at cost ÷ net sales for the same period. The US Census Bureau builds its retail ratios from the same two kinds of figure: stock valued at cost, sales at selling price. Some guides show the result as a percentage, so 0.72 becomes 72%; the meaning is the same.
| Input | What it means | Where it comes from |
|---|---|---|
| Average inventory | Stock at cost on a typical day of the period | (Opening stock + closing stock) ÷ 2, both at cost |
| Net sales | What customers paid for, after returns | Gross sales − sales returns, for the same dates |
| Period | The stretch of time both figures cover | A month, a quarter or a year: state it every time |
Keep stock at cost, never at its price tag. Valuing it at selling price inflates the ratio by your markup, and nobody else's figure can then be compared with yours.
Subtract returns before you divide. Returned goods are sales that didn't stay sold, and leaving them in makes the ratio look leaner than it is.
Use the average of opening and closing stock, not the closing figure alone. A big delivery on the last day of the month would otherwise make one good month look overstocked.
A worked example in Uganda shillings
For example, take a minimarket in Kampala over one month. The figures are illustrative, not a real shop's.
| Step | Calculation | Result |
|---|---|---|
| 1. Average inventory | (42,000,000 opening + 48,000,000 closing) ÷ 2 | UGX 45,000,000 |
| 2. Net sales | 63,700,000 gross sales − 1,200,000 returns | UGX 62,500,000 |
| 3. Inventory to sales ratio | 45,000,000 ÷ 62,500,000 | 0.72 |
| 4. In days of sales | 0.72 × 30 days | About 22 days |
The shop holds about 22 days of sales on its shelves and in its store room. With distributors calling every week, that is roughly three deliveries' worth of stock.
Copy the four rows into a spreadsheet and replace the figures with yours. Keep both numbers for the same dates and the same branch.
Say the period, or the ratio means nothing
The same shop gives three different ratios depending on the sales period you divide by. The stock doesn't change; only the length of the sales figure does.
| Sales period | Net sales (UGX) | Ratio | Months of sales in stock |
|---|---|---|---|
| One month | 62,500,000 | 0.72 | 0.72 |
| One quarter | 187,500,000 | 0.24 | 0.72 |
| One year | 750,000,000 | 0.06 | 0.72 |
To compare ratios built on different periods, convert each one to months of sales. Multiply a quarterly ratio by 3 and a yearly one by 12, and all three rows agree: 0.72 months, about 22 days.
What the 0.167 to 0.25 rule really says
A benchmark copied from guide to guide says a good inventory to sales ratio is 0.167 to 0.25. Amazon's guide for sellers repeats it with no source. It also lets the reader pick "a few weeks, a sales quarter, or an entire year" as the period.
Read on each period, the rule describes very different shops.
| If the sales period is | 0.167 to 0.25 means | The Kampala shop's verdict |
|---|---|---|
| A month | 5 to 7.5 days of sales in stock | 0.72: far too much stock |
| A quarter | 15 to 22.5 days of sales in stock | 0.24: inside the range |
| A year | 2 to 3 months of sales in stock | 0.06: far too little stock |
One shop, one shelf, three verdicts. Ignore the range until someone states its period, and judge your ratio against shops that sell what you sell.
What is a good inventory to sales ratio?
A good ratio is close to that of shops selling the same goods, and steady or falling while your shelves stay full. One public benchmark is published every month: the US Census Bureau's ratios by kind of store, built on one month's sales.
Its Manufacturing and Trade Inventories and Sales release of 15 October 2026 gives these figures for August 2026, seasonally adjusted. The Bureau reads each ratio as months of stock on hand against one month's sales (its definitions).
| Kind of business | Ratio (months of sales) | About (days of sales) |
|---|---|---|
| Food and beverage stores | 0.82 | 25 |
| Merchant wholesalers | 1.18 | 36 |
| All retail, excluding motor vehicles and parts | 1.19 | 36 |
| All retail | 1.36 | 41 |
| General merchandise stores | 1.39 | 42 |
| Furniture, electronics and appliance stores | 1.80 | 55 |
| Clothing and accessories stores | 2.02 | 61 |
| Building materials and garden supplies | 2.53 | 77 |
| Department stores | 2.60 | 79 |
The Kampala minimarket's 0.72 sits just under US food stores' 0.82. A hardware shop at 2.5 would match US building supply stores, while a minimarket at 2.5 would hold three times what US food stores hold.
These are averages for US businesses, not targets for an African shop. Long import lead times through Mombasa or Dar es Salaam push a ratio up for good reason. Your own trend, month after month, matters more than any single figure.
Inventory to sales ratio vs inventory turnover and DIO
The three measures describe the same stock from different sides. Turnover and DIO divide by cost of goods sold, while the inventory to sales ratio divides by sales at selling price.
| Measure | Formula | The Kampala month | Moves when prices change? |
|---|---|---|---|
| Inventory to sales ratio | Average inventory ÷ net sales | 0.72, about 22 days of sales | Yes |
| Inventory turnover | Cost of goods sold ÷ average inventory | 50,000,000 ÷ 45,000,000 = 1.11 in the month | No |
| Days inventory outstanding | Average inventory ÷ cost of goods sold × days | 45,000,000 ÷ 50,000,000 × 30 = 27 days | No |
The shop's gross margin is 20%, so its cost of goods sold for the month is UGX 50,000,000. Expressed in days, the ratio equals DIO × (1 − gross margin): 27 × 0.8 = 21.6 days.
The difference matters when prices move. If the shop raises prices 10% and sells the same goods, the ratio falls from 0.72 to 0.65. Nothing changed on the shelf, and DIO stays at 27 days.
Use the ratio when you have no cost of goods sold figure, or to compare with published retail figures. Use inventory turnover and the days inventory outstanding formula when prices are moving, as they do when the shilling weakens and suppliers reprice.
All three belong in the short list of inventory management KPIs, but a small shop needs only one of them. The balance sheet version, the inventory to working capital ratio, asks a different question: how much of your short-term money is stock.
What a rising or falling ratio tells you
Read the ratio month by month, beside sales. The direction of each tells you what to check first.
| Ratio | Sales | What it usually means | Check first |
|---|---|---|---|
| Rising | Rising | Stock bought ahead of a season or a price rise | That the extra stock sells before the season ends |
| Rising | Flat or falling | Buying more than you sell; slow lines piling up | Stock older than 90 days |
| Falling | Rising | Sales outrunning stock | Products at zero and customers turned away |
| Falling | Falling | Stock cut as sales drop | That best sellers stay on the shelf |
A ratio rising on flat sales usually ends in dead stock. Every month it sits adds holding cost: interest on the money, rent, power and risk.
A ratio that falls because shelves are empty is not progress, because the sales you lose never appear in the figure. Avoiding overstocking and stockouts sets the reorder points that keep both in check.
A rise before a festive season is fine when you planned it. Base the extra buying on the same weeks last year, as the guide to inventory forecasting methods shows, and watch the ratio fall back afterwards.
How to calculate the inventory to sales ratio in ArmPOS
ArmPOS has no screen that divides these two figures for you. Two reports give both inputs for any dates and any branch, and the division takes a minute.
- Get the stock at cost. Open Reports › Analytics Report, pick the month and the warehouse, and read Opening Stock and Closing stock (By purchase price). Average the two (Sales reports).
- Get net sales. Open Reports › Profit and Loss for the same dates and warehouse. Its Revenue tile is sales minus sales returns (Reports to check every day).
- Divide, and write down the period. Average stock ÷ Revenue for one month gives months of sales; multiply by 30 for days.
- Keep one row a month. Run both reports on the first of each month and add the figures to a spreadsheet, branch by branch.
- When the ratio rises, look at age. The Stock Aging Report sorts what you hold into up to 30, 30 to 60, 60 to 90 and over 90 days. The Dead Stock Report lists what hasn't moved (Stock reports).
- Trust closing stock after a count. Count a warehouse from a count sheet and correct it with an adjustment (Count and adjust stock). Stock taking vs stock checking explains which count to run.
A system that records every sale and delivery keeps month-end stock without a full count. Inventory management tools for small business compares the kinds of tool that do it.
Frequently asked questions
Is a high inventory to sales ratio bad?
Against shops like yours, a high ratio usually means cash tied up in stock that sells slowly. It is fine for a few weeks before a season, if the stock sells by the end of it.
Is the inventory to sales ratio the same as the stock to sales ratio?
Usually, yes. Retail buyers also use a version that divides the stock at the start of a month, at selling price, by that month's sales. Check which one a figure uses before you compare.
Should inventory be valued at cost or at selling price?
At cost. Stock at selling price inflates the ratio by your markup, and the Census Bureau values retail inventories at cost.
Can I work it out for one product?
Yes, in units: units on hand ÷ units sold last month gives months of stock for that product. Units ignore price changes, which helps when supplier prices move with the exchange rate.
What is the latest US inventory to sales ratio?
For August 2026, the Census Bureau put all US retail at 1.36, and all business at 1.33 against 1.40 in August 2025. It publishes new figures each month, about six weeks after the month ends.
Work out last month's ratio this week, in months of sales, and repeat it on the first of each month. Create a free ArmPOS account to read opening and closing stock at cost for any month; shops in Uganda can start from ArmPOS in Uganda.
