Free printable
Retail maths cheat sheet
The formulas planners and allocators use every week, on one page. Print it or save it as a PDF and keep it next to your keyboard.
Gross margin %
(Selling price − cost) ÷ selling price × 100Profit as a share of the price. Use prices before tax.
Markup %
(Selling price − cost) ÷ cost × 100Profit as a share of the cost. Always bigger than margin.
Markup to margin
Margin % = markup % ÷ (100 + markup %) × 100A 100% markup is a 50% margin.
Price for a target margin
Price = cost ÷ (1 − margin as a decimal)Cost $40 at 60% margin: 40 ÷ 0.4 = $100.
Average selling price (ASP)
Sales $ ÷ units soldWatch it fall when markdowns start.
Sell-through %
Units sold ÷ units received × 100Use units received, not units on hand.
Rate of sale (ROS)
Units sold ÷ (stores × weeks)Units per store per week: the building block of buys and allocations.
Weeks of cover
Stock on hand ÷ forecast weekly salesHow long the stock lasts at the current rate.
Stock-to-sales ratio
Start-of-month stock ÷ month salesBoth at retail value.
Stock turn
Sales ÷ average stock (same basis)Both at retail, or both at cost. Annualise a season figure.
GMROI
Gross margin $ ÷ average stock at costEquals margin % × (sales at retail ÷ average stock at cost).
Open-to-buy (OTB)
Planned closing stock + planned sales + planned markdowns − opening stock − on orderWhat you can still buy for the period.
Markdown cost
Units × (old price − new price)Plan it as dollars, not just a percentage.
Achieved margin
Intake margin − markdowns − shrinkage − discounts (in % points)Name every point of erosion.
Average transaction value (ATV)
Sales $ ÷ number of transactionsPairs with UPT to explain sales changes.
Units per transaction (UPT)
Units sold ÷ number of transactionsLike-for-like growth %
(This year − last year) ÷ last year × 100Same stores, same weeks, so new stores do not flatter it.
Reorder point
Weekly sales × lead time in weeks + safety stockOrder when stock falls to this level.
Buy quantity
ROS × stores × weeks ÷ target sell-throughDemand grossed up for the stock you expect to have left.
From Merchandise Planning Mastery, merchandiseplanninginstitute.com. Prices in the examples are before tax.