function calculateSellThroughRate() {
var soldInput = document.getElementById('unitsSold');
var inventoryInput = document.getElementById('startingInventory');
var resultBox = document.getElementById('resultDisplay');
var percentDisplay = document.getElementById('strPercentage');
var detailsDisplay = document.getElementById('inventoryDetails');
var sold = parseFloat(soldInput.value);
var total = parseFloat(inventoryInput.value);
// Validation
if (isNaN(sold) || isNaN(total)) {
alert("Please enter valid numbers for both fields.");
return;
}
if (total <= 0) {
alert("Beginning Inventory must be greater than zero.");
return;
}
if (sold total) {
alert("Units sold cannot exceed total inventory.");
return;
}
// Calculation
var rate = (sold / total) * 100;
var remaining = total – sold;
var formattedRate = rate.toFixed(2);
// Interpretation
var analysis = "";
if (rate < 40) {
analysis = "Slow Mover: Consider markdowns or promotions to clear stock.";
} else if (rate >= 40 && rate <= 80) {
analysis = "Healthy: Sales velocity is optimal.";
} else {
analysis = "High Demand: Risk of stockout. Consider restocking immediately.";
}
// Update DOM
resultBox.style.display = "block";
percentDisplay.innerHTML = formattedRate + "%";
detailsDisplay.innerHTML =
"Analysis: " + analysis + "" +
"Units Sold: " + sold + "" +
"Remaining Stock: " + remaining + "" +
"Total Beginning Stock: " + total;
}
How is Sell-Through Rate Calculated?
Sell-Through Rate (STR) is a fundamental retail metric that compares the amount of inventory a retailer receives against what is actually sold within a specific period. It is a key indicator of supply chain efficiency, product popularity, and inventory management performance.
Unlike inventory turnover, which looks at how many times you replace stock over a year, sell-through rate is often used for shorter periods (usually monthly) to track the velocity of specific items or categories.
The Formula
The calculation for sell-through rate is straightforward. It is the percentage of your non-sold inventory that converted into sales.
(Units Sold / Units Received) × 100 = Sell-Through Rate %
Where:
Units Sold: The number of items sold during the specific time period.
Units Received (or Beginning Inventory): The total stock available for sale at the start of that period.
Detailed Calculation Example
Let's calculate the sell-through rate for a boutique clothing store launching a new summer line.
Scenario: The store buys 500 units of a specific summer dress at the beginning of June.
Action: By the end of June, the Point of Sale (POS) system shows that 320 of those dresses were sold.
Using the formula:
(320 / 500) × 100 = 64%
The sell-through rate for June is 64%. This means the store sold nearly two-thirds of its inventory in the first month.
What is a "Good" Sell-Through Rate?
Sell-through rates vary significantly by industry and product type, but general benchmarks in retail suggest:
Under 40%: This is often considered low. It indicates that you have overstocked, priced the item too high, or there is low market demand. You are paying carrying costs for inventory that isn't moving.
40% to 80%: This is the "sweet spot" for most retailers. It suggests a healthy balance where inventory is moving fast enough to generate profit but not so fast that you lose sales due to stockouts.
Over 80%: While high sales are good, a rate this high might indicate you understocked. If you sell out too quickly, you miss potential sales from customers who arrive after the shelves are empty.
Why This Metric Matters
Calculating sell-through rate regularly allows retailers to:
Optimize Markdowns: Identify slow-moving items (low STR) early and discount them to free up cash and shelf space.
Improve Buying Decisions: If a specific brand or category consistently has a high STR, buyers know to increase order quantities for the next season.
Reduce Storage Costs: Inventory that sits in a warehouse costs money. Increasing STR lowers holding costs.