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Personal Finance
How stores set prices, why a 50%-off sale can still earn a profit, and the math that tells a real deal from retail theatre.
By FreeCalculators Editorial · Published 2026-08-22 · Updated 2026-08-22 · 4 min read · 956 words
A markup is what a store adds to its cost to arrive at a price; a discount is what it subtracts from that price to lure you back. They are the same arithmetic seen from opposite sides of the counter — and once you understand both, a sale tag stops being a verdict and becomes information you can price-check in seconds.
Markup measures profit against cost: price minus cost, divided by cost. Margin measures it against price: price minus cost, divided by price. An item costing $60 that sells for $100 carries a 66.7% markup but a 40% margin. Retailers live in margin because rent and payroll come out of revenue, while shoppers reason in markup because it sounds like the store's greed coefficient. The full translation table lives in our guide to margin versus markup pricing.
Many retailers price by keystone — doubling wholesale cost — which leaves room to discount heavily and still earn. Worse, the reference price on the tag may barely exist: a "was $129" anchor can be a number the shelf never seriously charged. Retail history's cleanest proof came in 2012, when JCPenney abolished fake anchors and constant sales in favour of honest everyday low prices — and revenue promptly fell by roughly a quarter. Shoppers did not trust low prices; they trusted the thrill of a discount off an inflated one.
| Pricing posture | Tag on a $40-cost item | Shopper reality |
|---|---|---|
| Keystone (2× cost) | Sells at $80 | The store's fair baseline. |
| Anchor price | "Was $129" | Often never charged at volume. |
| Promotional price | "$59.99 — save 54%!" | Store margin is still about 33%. |
The single most expensive mistake in sale-shopping is treating 30% off plus 20% off as 50% off. Discounts apply in sequence, each to whatever price survives the last, so they multiply: 0.70 × 0.80 = 0.56, leaving you paying 56% of the original. The order never matters — only the product of the factors does.
The coat that was never 50% off
Ticket price: $200 After 30% promo: 200 × 0.70 = $140 After extra 20% coupon: 140 × 0.80 = $112 True total discount: 44%, not 50%
Flip the counter and this math is your income statement. Anyone selling — Etsy goods, freelance work, a small brand — sets prices by markup over true cost, then guards margin against their own temptation to discount. Discounting from a price chosen to protect margin is a tactic; discounting blindly is donating profit. The industry benchmarks worth knowing sit in our survey of profit margins by industry, and the playbook for correcting an underpriced offer is covered in raising prices without losing customers.
Retail math is symmetric and small: cost, price, percentage, multiplication. Shoppers who run those four numbers stop paying for theatre, and sellers who respect them stop giving margin away.
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This guide was written and reviewed by FreeCalculators Editorial, drawing on published formulas, official government sources, and real calculator outputs from our 4 calculators in this category. Every claim is sourced; every formula is auditable. Read our review policy.