Enter current inventory to calculate Weeks of Cover.
Average Rate of Sale:–
Standardized Weekly ROS:–
Est. Weeks of Cover:–
Excel Formula to Copy:=A2/B2
function calculateRateOfSale() {
// 1. Get Input Values using var
var unitsSoldInput = document.getElementById('rosUnitsSold');
var timeValueInput = document.getElementById('rosTimeValue');
var timeUnitInput = document.getElementById('rosTimeUnit');
var currentStockInput = document.getElementById('rosCurrentStock');
var unitsSold = parseFloat(unitsSoldInput.value);
var timeValue = parseFloat(timeValueInput.value);
var timeUnit = timeUnitInput.value;
var currentStock = parseFloat(currentStockInput.value);
// 2. Validation
if (isNaN(unitsSold) || isNaN(timeValue) || timeValue 0) {
var cover = currentStock / weeklyROS;
weeksOfCover = cover.toFixed(1) + " Weeks";
} else if (!isNaN(currentStock) && weeklyROS === 0) {
weeksOfCover = "Infinite (No Sales)";
}
// 4. Generate Excel Formula String
var excelFormula = "";
if (timeUnit === 'weeks') {
excelFormula = "=Units_Cell / Weeks_Cell";
} else if (timeUnit === 'days') {
excelFormula = "=(Units_Cell / Days_Cell) * 7";
} else {
excelFormula = "=(Units_Cell / Months_Cell) / 4.33″;
}
// 5. Display Results
document.getElementById('resAvgRos').innerHTML = rawROS.toFixed(2) + " units / " + timeUnit.slice(0, -1);
document.getElementById('resWeeklyRos').innerHTML = weeklyROS.toFixed(2) + " units / week";
document.getElementById('resStockCover').innerHTML = weeksOfCover;
document.getElementById('resExcelFormula').innerHTML = excelFormula;
document.getElementById('rosResults').style.display = 'block';
}
How to Calculate Rate of Sale in Excel
Understanding your Rate of Sale (ROS) is critical for effective inventory management, retail forecasting, and supply chain optimization. Whether you are a small business owner using spreadsheets or a retail planner, knowing how fast your product sells allows you to prevent stockouts and avoid overstocking.
What is Rate of Sale?
Rate of Sale (ROS) is a metric that calculates the average number of units sold over a specific period. In retail, this is most commonly expressed as Units Per Week (UPW) or Average Weekly Sales (AWS).
The basic logic is straightforward:
ROS = Total Units Sold รท Time Period
Calculating Rate of Sale in Excel: Step-by-Step
Excel is the most common tool for calculating ROS because it can handle large datasets of SKU performance. Here is how to set up your spreadsheet.
1. Basic Weekly ROS Formula
If you have your sales data organized by weeks, the formula is a simple division.
Column A: Product Name
Column B: Total Units Sold
Column C: Number of Weeks Selling
Column D: Rate of Sale
In cell D2, enter the following formula:
=B2/C2
Example: If you sold 150 units over 10 weeks, the result is 15 units per week.
2. Calculating ROS from Date Ranges
Often, you don't have the "number of weeks" pre-calculated, but rather a Start Date and an End Date. You can calculate the time period dynamically inside Excel.
Cell B2: Total Units Sold (e.g., 500)
Cell C2: Start Date (e.g., 01/01/2023)
Cell D2: End Date (e.g., 03/31/2023)
To calculate the weekly rate of sale, use this formula:
=B2 / ((D2 – C2) / 7)
Explanation:(D2 - C2) calculates the number of days between the dates. Dividing by 7 converts those days into weeks.
Advanced: Adjusted Rate of Sale (Handling Stockouts)
One common mistake when calculating Rate of Sale in Excel is including weeks where the item was out of stock. If an item was out of stock, it had zero sales, but not because of low demand.
To get a "True ROS," you must subtract the out-of-stock weeks from the time period:
=Total_Sales / (Total_Weeks – Weeks_Out_Of_Stock)
Why Monitor Rate of Sale?
Benefit
Description
Stock Cover Analysis
By dividing your current inventory by your weekly ROS, you know exactly how many weeks of supply you have left before you run out.
Reordering
High ROS items need frequent replenishment. Low ROS items ("slow movers") may need markdowns to clear space.
Performance Comparison
ROS allows you to compare products fairly, even if they have been on the shelf for different lengths of time.
Conclusion
Mastering the Rate of Sale calculation in Excel is a fundamental skill for retail analytics. By using the formulas above, or the calculator provided at the top of this page, you can gain immediate visibility into product performance and make data-driven purchasing decisions.