Retail calculators

Free, no sign-up calculators for the numbers retail teams use every week. Each one shows the formula and a worked example, and most also include an industry benchmark (Markup and Open-to-Buy don't, as they depend on your own pricing and buying plan).

Finance & Retail Math

The math behind every retail decision.

  • Markup Calculator — Amount added on top of cost to set the selling price, expressed as a % of cost. Markup and margin are not the same thing. Confusing the two is the #1 pricing mistake retailers make. Formula: (Price − Cost) ÷ Cost × 100
  • Gross Margin Calculator (GM%) — Percentage of revenue left after subtracting the cost of goods sold (COGS). The cleanest signal of product profitability. If GM% drops, every downstream cost — payroll, rent, marketing — gets harder to cover. Formula: (Revenue − COGS) ÷ Revenue × 100

Commercial

Pricing, margin, and buying performance.

  • Gross Margin Return on Investment Calculator (GMROI) — Gross margin generated for every riyal invested in inventory. Combines profit and turn into one number — the gold standard for evaluating buying performance. Formula: Gross Margin SAR ÷ Average Inventory Cost
  • Sell-Through Rate Calculator (ST%) — Percentage of received inventory that has sold over a period. Drives reorder, markdown, and exit decisions. Low ST% early in the season = act fast. Formula: Units Sold ÷ Units Received × 100
  • Open-to-Buy Calculator (OTB) — Riyals available to spend on new inventory in a period. Prevents overbuying and stockouts. The discipline that keeps cash and assortment in balance. Formula: Planned Sales + Planned Markdowns + Planned EOM − Planned BOM − On Order
  • Discount Break-Even Calculator — How many more units you must sell to earn the same total margin after a discount. A discount is only free if the extra volume covers it. Most promotions that feel successful on revenue lose money on margin. Formula: Discount % ÷ (Margin % − Discount %) × 100

Merchandising

Right product, right place, right time.

  • Stock-to-Sales Ratio Calculator — Inventory on hand at the start of a month relative to sales for that month. Signals whether you have the right amount of stock for upcoming demand. Too high = markdowns; too low = stockouts. Formula: BOM Inventory ÷ Sales for the Month

Operations

Run a tight ship.

  • Inventory Turnover Calculator — Number of times inventory is sold and replaced over a period. Higher turn = healthier cash flow and fresher product. Low turn ties up capital and risks markdowns. Formula: COGS ÷ Average Inventory at Cost
  • Weeks of Supply Calculator (WOS) — How many weeks the stock on hand will last at the current rate of sale. The unit buyers actually plan in. It answers 'will this last until the next delivery?' in one number. Formula: Units on Hand ÷ Average Weekly Unit Sales
  • Shrinkage Rate Calculator — Inventory lost to theft, damage, admin error, or supplier fraud, as a % of sales. A silent margin killer. The industry average is ~1.5% of sales — every 0.1% reduction drops straight to profit. Formula: (Recorded Inventory − Actual Inventory) ÷ Net Sales × 100