What is a stock-to-sales ratio?

The stock-to-sales ratio is beginning-of-period (BOM) inventory divided by the sales for that period, in the same unit. It tells you how much stock you are carrying for every unit — or dollar — of sales, and it is the multiplier that drives BOM stock targets in a merchandise financial plan.

How do you calculate the stock-to-sales ratio?

Stock-to-sales ratio = BOM stock ÷ period sales. For example, carrying 12,000 units at the start of a month against 5,000 units of sales gives 12,000 ÷ 5,000 = 2.40x. Keep both figures in the same unit — either both units or both dollars — so the ratio is clean.

What is a good stock-to-sales ratio?

There is no universal target — it depends on your replenishment cadence, lead times, and how seasonal the category is. Read it against your own plan: a higher ratio means more cover relative to demand and more markdown exposure if sales soften, while a lower ratio runs leaner and closer to stockouts. Set the benchmark from your history, not an external number.

How does stock-to-sales relate to weeks of supply?

They measure the same thing on different scales. Multiply the stock-to-sales ratio by the number of weeks in the period and you get implied weeks of supply — a 2.40x ratio over a period of about 4.3 weeks is roughly 10 weeks of supply. Stock-to-sales is the planning form used in MFP; weeks of supply is the operational form buyers watch week to week.

Should the stock-to-sales ratio use units or dollars?

Either works, as long as both the stock and the sales use the same one. Dollar-based ratios are standard in a retail-method merchandise financial plan because they tie straight to OTB; unit-based ratios are useful at the style or size level where price mix would distort a dollar figure. Just do not mix units and dollars in the same ratio.

// Tools

Stock-to-sales ratio calculator

The stock-to-sales ratio is your beginning-of-period stock divided by the sales for that period — BOM stock ÷ period sales. It is the multiplier behind BOM stock targets in a merchandise financial plan. Enter stock and sales in the same unit (units or dollars) to get the ratio, and add the period length in weeks to see implied weeks of supply.

BOM stock (units or $)

Sales for the period (same unit)

Weeks in the period (optional)

wks

Enter beginning-of-period (BOM) stock and the sales for that same period in the same unit — both units or both dollars. Add the period length in weeks to see implied weeks of supply.

Enter BOM stock and period sales (same unit) to see the stock-to-sales ratio.

// How it works

01
Enter BOM stock
The beginning-of-period (BOM) inventory you are carrying into the period — units or dollars.
02
Enter period sales
The sales for that same period, in the same unit as the stock (both units or both dollars).
03
Read the ratio
Stock-to-sales ratio = BOM stock ÷ period sales. It is the stock you hold per unit of sales.
04
Add the period length in weeks (optional)
Enter how many weeks the period spans to convert the ratio into implied weeks of supply (ratio × weeks in period).

// Formula & example

Formula & a worked example

Stock-to-sales ratio = BOM stock ÷ period sales. Take a knit program carrying 12,000 units at the start of the month against 5,000 units of sales that month: the ratio is 12,000 ÷ 5,000 = 2.40x. You are holding 2.4 units of stock for every unit you expect to sell in the period.

To read that on the operational scale buyers use, multiply by the weeks in the period. A month spans about 4.3 weeks, so implied weeks of supply = 2.40 × 4.3 ≈ 10.3 weeks. Same inventory position, two lenses: the ratio drives the plan's BOM target, and weeks of supply is what the buyer watches against lead time.

// Reading the result · where spreadsheets break

Read the ratio against your own plan, not an external ideal. A higher stock-to-sales ratio means you are carrying more cover relative to demand — protection against stockouts, but more markdown exposure if sales soften. A lower ratio runs leaner and turns faster, at the cost of thinner safety stock. The right level follows from your replenishment cadence, lead times, and how seasonal the category is.

In a spreadsheet, the BOM stock target lives in the MFP tab while actual on-hand and sales land somewhere else, and the ratio only gets checked when someone reconciles them. By then the buy is placed. The value is in seeing planned stock-to-sales, actual sell-down, and the resulting weeks of supply on one plan while there is still time to chase or cancel.

RetailNorthstar ties stock-to-sales targets to the plan, so BOM stock, sell-down, and weeks of supply stay linked from the merchandise financial plan through in-season chase — see more retail tools.

Book a Demo →See RetailNorthstar →

// FAQ

Frequently asked questions

What is a stock-to-sales ratio?: The stock-to-sales ratio is beginning-of-period (BOM) inventory divided by the sales for that period, in the same unit. It tells you how much stock you are carrying for every unit — or dollar — of sales, and it is the multiplier that drives BOM stock targets in a merchandise financial plan.
How do you calculate the stock-to-sales ratio?: Stock-to-sales ratio = BOM stock ÷ period sales. For example, carrying 12,000 units at the start of a month against 5,000 units of sales gives 12,000 ÷ 5,000 = 2.40x. Keep both figures in the same unit — either both units or both dollars — so the ratio is clean.
What is a good stock-to-sales ratio?: There is no universal target — it depends on your replenishment cadence, lead times, and how seasonal the category is. Read it against your own plan: a higher ratio means more cover relative to demand and more markdown exposure if sales soften, while a lower ratio runs leaner and closer to stockouts. Set the benchmark from your history, not an external number.
How does stock-to-sales relate to weeks of supply?: They measure the same thing on different scales. Multiply the stock-to-sales ratio by the number of weeks in the period and you get implied weeks of supply — a 2.40x ratio over a period of about 4.3 weeks is roughly 10 weeks of supply. Stock-to-sales is the planning form used in MFP; weeks of supply is the operational form buyers watch week to week.
Should the stock-to-sales ratio use units or dollars?: Either works, as long as both the stock and the sales use the same one. Dollar-based ratios are standard in a retail-method merchandise financial plan because they tie straight to OTB; unit-based ratios are useful at the style or size level where price mix would distort a dollar figure. Just do not mix units and dollars in the same ratio.

// Related resources

See the connected workflow in RetailNorthstar →