The math professionals run: markups, margins and sell-through

# The math professionals run: markups, margins and sell-through

A buyer at a mid-market retailer places an order for 2,000 dresses at $30 each. She retails them at $79.99. Six weeks later, half are still hanging on the rack. Every decision she makes next (mark them down? reorder the fast colors? hold for full price?) runs on a handful of calculations she can do in her head. This lesson teaches you those calculations on exactly that kind of buy.

None of this is advanced. It is arithmetic. But fluency here separates people who can talk to a merchandising team from people who cannot.

The vocabulary you cannot fake

A few terms, defined once, then used throughout.

• Cost: what the retailer pays the supplier per unit (also called wholesale or landed cost).
• Retail or ticket price: the price on the tag.
• Markup: the amount added to cost to get to retail.
• Margin (or gross margingross marginGross margin is the share of revenue left after subtracting the direct cost of producing goods or services, expressed as a percentage of revenue.View full definition →): profit as a percentage of the selling price.
• Markdown: a permanent price reduction taken to move stock.
• Sell-through: the percentage of units sold out of the units received.
• SKU (Stock Keeping Unit): one specific variant, for example "black dress, size M." A single style in 4 colors and 6 sizes is 24 SKUs.

Markup vs margin: the classic trap

These get confused constantly, so slow down here.

Keystone markup is the industry's oldest rule of thumb: double the cost. Cost $30, retail $60. That is a 100% markup.

But the margin on keystone is not 100%. Margin is measured against the retail price, not the cost.

Worked example on our dress:

• Cost: $30
• Retail: $79.99 (round to $80)
• Markup in dollars: $80 minus $30 = $50
• Markup % = markup / cost = 50 / 30 = 167%
• Gross margin % = markup / retail = 50 / 80 = 62.5%

Same dress, two very different numbers. When a wholesaler says "we run at keystone," they mean markup. When a CFO talks about the health of the business, they mean margin. Mixing them up in a meeting is a tell that you do not know the sector.

A quick sanity check most merchants memorize: a 50% margin is only a 100% markup. To get a higher margin, you need a disproportionately bigger markup.

For a clean primer on the mechanics, the U.S. Small Business Administration's guidance on pricing and margins is a free, plain-English reference.

Initial markup vs maintained margin

Here is where beginners lose money on paper without realizing it.

The initial markup (IMU) is the margin you set when the goods hit the floor. But almost nobody sells everything at full price. Markdowns, theft (called shrink), and employee discounts eat into it. What you actually keep is the maintained margin.

So the 62.5% above is a fantasy number until the season is over. If you mark half the dresses down, your real margin drops. We will calculate exactly how much next.

Markdowns and the markdown rate

Back to the buyer. She bought 2,000 units. After six weeks, 1,000 sold at $80. The rest are stuck. She marks the remaining 1,000 down to $48 (a 40% price cut) and eventually sells them all.

Revenue:

• 1,000 units at $80 = $80,000
• 1,000 units at $48 = $48,000
• Total revenue = $128,000

Cost of goods: 2,000 units at $30 = $60,000

Maintained gross margin:

• Gross profit = $128,000 minus $60,000 = $68,000
• Margin = 68,000 / 128,000 = 53%

Compare that to the 62.5% she planned. The markdowns cost her roughly 9.5 margin points. That gap is the single most watched number in apparel retail.

The markdown rate here:

• Dollars given up to markdown = 1,000 units × $32 (the $80 to $48 cut) = $32,000
• Markdown rate = markdowns / total sales at full ticket = often expressed as markdown dollars over net sales.

Industry markdown rates in apparel are commonly estimated in the 30% to 40% range of goods for many mainstream retailers (an estimate, and it varies widely by channel and year). Full-price luxury houses run far lower; off-price chains structure their whole model around it.

Sell-through: the pulse of the buy

Sell-through rate = units sold / units received.

At the six-week mark, our buyer had sold 1,000 of 2,000: a 50% sell-through. Whether that is good depends entirely on the time window and the product.

Rough rules of thumb professionals cite (estimates, not laws):

• A common healthy target is around 60% to 70% sell-through at full price before markdowns begin.
• Fast-fashion players expect very high weekly sell-through and reorder aggressively on winners.
• A 50% sell-through at six weeks on a seasonal dress is soft. It signals the markdown was probably necessary.

The follow-up metric is weeks of supply (WOS):

WOS = units on hand / average units sold per week.

If she has 1,000 units left and is selling 60 a week at the new price, that is roughly 16 weeks of supply. If the season ends in 8 weeks, she has too much stock and a deeper markdown is coming. WOS turns a static inventory number into a countdown clock.

🎬 [VIDEO: "Retail Math Basics: Markup, Margin, Sell-Through" - https://www.youtube.com/results?search_query=retail+math+markup+margin+sell+through - a short walkthrough of the core retail calculations with worked examples]

Open-to-buy: the budget that governs everything

Open-to-buy (OTB) is the dollar amount a buyer is still allowed to spend for a given period, given sales targets and inventory already committed. It is the guardrail that stops merchants from over-ordering.

The simple formula:

OTB (at retail) =
    Planned end-of-month inventory
  + Planned sales for the month
  + Planned markdowns
  - Beginning-of-month inventory
  - Merchandise already on order (on the way in)

Quick example. A department is planned to:

• End the month with $200,000 in inventory (at retail)
• Sell $150,000 that month
• Take $20,000 in markdowns
• Start the month with $280,000 in inventory
• Have $60,000 of stock already on order

OTB = 200,000 + 150,000 + 20,000 minus 280,000 minus 60,000 = $30,000.

She has $30,000 of retail value left to buy. Anything more and she blows the inventory plan, ties up cash, and guarantees future markdowns. OTB is where math meets discipline.

The market context these numbers sit in

The calculations are universal, but scale matters when you benchmark.

• Global apparel and footwear is a very large market, commonly estimated in the range of $1.7 trillion to $1.8 trillion in annual retail value (estimate, varies by source and definition).
• The United States apparel market is frequently estimated at roughly $350 billion to $400 billion per year (estimate).
• Europe collectively is broadly comparable in scale to the US, with major markets in Germany, the UK, France, Italy, and Spain (estimate; definitions and currency conversion affect totals).
• Growth in mature US and European apparel is typically low single digits in normal years, with e-commerce penetration a big driver of where the growth lands (estimate).

For consistent, sourced sizing, the OECD and national statistics offices publish retail trade data; industry bodies like the American Apparel & Footwear Association publish sector figures. Always check the as-of date and whether a figure is retail value, wholesale, or units.

Due diligence: the checks pros actually run

Before you trust anyone's margin story, run these.

• Is that markup or margin? Ask which. A "50% markup" and a "50% margin" are very different businesses.
• Gross or maintained? A beautiful IMU means nothing if markdown rates are quietly high.