Retail Merchandising & Inventory Velocity Lab

Sell-Through Rate Lab

Calculate retail Sell-Through Rate (STR), Weeks of Supply (WOS), Stock-to-Sales Ratio, and optimize markdown timing and clearance margin in a free lab.

Velocity Model Merchandising Audit STR & WOS Theory FAQ

Retail Presets

Load calibrated seasonal product categories.

Step 1: Inventory Receipts, Sales & Season Cadence

Inventory Position & Markdown Parameters

Inventory Stock & Unit Sales

Season Cadence & Target STR

%

Pricing & Planned Markdown Liquidation

$
$
%
Sell-Through Rate (STR)
35.0%
Target: 85% (Week 4 of 8)
Weeks of Supply (WOS)
7.4 wks
4 Weeks Remaining in Season
Ending Inventory (EOH)
3,250 units
Projected Unsold: 1,500 units
Merchandise Velocity Status
Slow Mover / Overstocked
Action: Trigger 25% Markdown

Inventory Velocity & Markdown Decision Audit

Merchandise Metric Calculated Value Operational Context

Retail Merchandising Strategy

Mastering STR & Weeks of Supply

Sell-Through Rate and Weeks of Supply form the analytical foundation of retail merchandise planning, allowing buyers to identify fast movers and liquidate aged inventory before season end.

  • Sell-Through Rate (STR %): The velocity of inventory conversion. High STR early in the season confirms product-market fit; lagging STR signals overstock risk.
  • Weeks of Supply (WOS): How long existing stock will last at current weekly sales rates. Ideal WOS aligns precisely with the remaining selling season.
  • The Markdown Dilemma: Delaying markdowns leads to deeper, margin-destroying discounts later. Proactive early markdowns clear units while preserving cash margin.
  • Cash Flow Liberation: Liquidating stagnant stock recovers working capital to reinvest in fresh high-velocity merchandise.

Plan seasonal inventory budgets in the Open-To-Buy Lab.

Retail Inventory Formulas

Essential merchandising formulas

Total Available = Beginning Inventory + Received Receipts

Sell-Through Rate (STR %) = (Units Sold ÷ Total Available) × 100

Ending Inventory (EOH) = Total Available - Units Sold

Weekly Sales Velocity = Units Sold ÷ Elapsed Weeks

Weeks of Supply (WOS) = Ending Inventory ÷ Weekly Velocity

Remaining Weeks = Total Season Weeks - Elapsed Weeks

Markdown Price = Retail Price × (1 - Markdown %)

Clearance Cash Flow = Ending Inventory × Markdown Price

Evaluate inventory turns in the Inventory Turnover & GMROI Lab.

FAQ

Retail sell-through and markdown questions

What is Sell-Through Rate (STR) in retail?

Sell-Through Rate (STR %) measures the proportion of received inventory sold over a specific period: STR = Units Sold ÷ (Beginning Inventory + Received Inventory) × 100.

How do you calculate Weeks of Supply (WOS)?

Weeks of Supply (WOS) = Current Ending Inventory ÷ Average Weekly Unit Sales. WOS indicates how many weeks current inventory will last at the current sales velocity.

When should a retailer trigger a markdown?

A markdown is triggered when WOS exceeds the remaining weeks in the selling season (WOS > Remaining Weeks × 1.3), signaling that existing stock will not clear at full price before the season ends.

What is the relationship between STR and Open-To-Buy (OTB)?

High STR items generate faster cash turn and free up Open-To-Buy (OTB) budget for reorders, while low STR items tie up working capital in stagnant stock.

Can I export retail sell-through audits to CSV?

Yes. You can export complete beginning inventory, sales velocity, STR percentages, WOS, projected surplus units, and markdown cash recoveries as a UTF-8 CSV spreadsheet with formula injection defense.

Is this tool certified retail merchandising software?

No. This tool provides educational retail inventory simulations for merchandise analysis without certified retail merchandising warranties.

Continue Exploring Retail & Inventory Tools

Explore our Retail & Inventory Hub, manage seasonal buying budgets in the Open-To-Buy Lab, calculate gross margin returns in the Inventory Turnover & GMROI Lab, or calculate safety stock in the Safety Stock Lab.