A product costs you $60 and sells for $100. Ask ten small-business owners what the margin is and several will say 66.7%. Ask what the markup is and several will say 40%. Both groups have it exactly backwards — and that reversal, applied across a whole catalog, is one of the most expensive spreadsheet errors in small business.
The two words describe the same $40 of profit from two different directions. Mix them up and every price you set is quietly wrong in the same direction: too low.
Same dollars, two denominators
Margin is profit as a percentage of the selling price. Markup is profit as a percentage of the cost. Same numerator, different denominator — and the denominator changes everything.
Take that $60 cost, $100 price example:
- Margin = ($100 − $60) ÷ $100 = 40%
- Markup = ($100 − $60) ÷ $60 = 66.7%
Forty dollars of profit either way. But "40%" and "66.7%" are describing it against different bases, and markup is always the bigger number for the same transaction. Always. If someone quotes you a "margin" that is higher than the equivalent markup, a wire is crossed somewhere.
The formulas, for reference:
- Margin = (Price − Cost) ÷ Price
- Markup = (Price − Cost) ÷ Cost
- To convert: Markup = Margin ÷ (1 − Margin), and Margin = Markup ÷ (1 + Markup)
The conversion table worth taping to your monitor
- 10% margin = 11.1% markup
- 15% margin = 17.6% markup
- 20% margin = 25% markup
- 25% margin = 33.3% markup
- 30% margin = 42.9% markup
- 40% margin = 66.7% markup
- 50% margin = 100% markup
Read that last line again. Doubling your money — buying at $50 and selling at $100 — is a 100% markup but only a 50% margin. Notice too how the gap widens as the numbers grow: at 10% the two are a rounding error apart, at 50% one is literally double the other. That is why the mistake goes unnoticed at thin margins and does real damage at healthy ones.
The classic error, with the money it loses
Here is how it usually happens. A business decides it needs a 25% margin to cover overhead and profit. Someone builds the pricing spreadsheet and multiplies every cost by 1.25 — a 25% markup, though nobody calls it that.
Take an item costing $80. The spreadsheet prices it at $80 × 1.25 = $100. Profit is $20. But margin is $20 ÷ $100 = 20%, not 25%.
The correct price for a 25% margin divides by (1 − 0.25) instead of multiplying by 1.25: $80 ÷ 0.75 = $106.67. Profit $26.67, margin exactly 25%.
So the spreadsheet is underpricing by $6.67 on every $100 of intended revenue — the business is collecting $20 of gross profit where it planned for $26.67, exactly 25% less gross profit than budgeted, on every single sale. Overhead was budgeted against the 25% figure, so the shortfall comes straight out of net profit. A company doing $800,000 a year on this spreadsheet is leaving roughly $53,000 in gross profit on the table and probably blaming rent.
The general rule: to hit a target margin M, price = cost ÷ (1 − M). Never price = cost × (1 + M). A margin calculator will do this correctly by default, which is the fastest way to sanity-check a price list you inherited from someone else's spreadsheet.
When to use which
Neither number is wrong; they answer different questions.
- Markup is a pricing tool. It works forward from cost, which is what you know when you are setting a price. "Cost times 1.5" is a fine shorthand — as long as you know that 50% markup means 33.3% margin.
- Margin is a health metric. It works backward from revenue, which is how your P&L is organized. Gross margin is what covers rent, payroll, and marketing, so budgets, breakeven analysis, and investor conversations all speak in margin.
The trouble is purely translational: pricing decisions made in markup land get reported in margin land, and if nobody converts between them, the P&L quietly disagrees with the price list.
The discount trap: where margin math gets brutal
Discounting is where confusing these concepts goes from expensive to fatal, because discounts come off the price while your costs do not move.
Take a product with a 30% margin: cost $70, price $100, $30 of profit per unit. Now run a "10% off" promotion:
- New price: $90. Cost: still $70. New profit: $20 per unit.
- New margin on the discounted price: $20 ÷ $90 = 22.2%.
A 10% discount did not cost you 10% of your profit. It cost you a third of it — profit per unit fell from $30 to $20. To make the same total gross profit, you now need $30 ÷ $20 = 1.5 times the unit volume. The sale has to move 50% more product just to break even against not running it at all.
Steepen the discount and the math gets ugly fast. At 20% off, the price is $80 against a $70 cost — $10 of profit, meaning you need three times the volume to break even. And if margins are thinner to begin with, there is less room still: a 25% margin product discounted 10% needs about 67% more volume.
Ask yourself honestly: does a 10% discount reliably lift your unit volume by 50%? For most businesses, most of the time, it does not. Which is why blanket discounts so often produce a busy month and a worse quarter. Before your next promotion, run the numbers through a percent-off calculator alongside your margin figures and see what volume lift you would actually need.
The five-minute audit
- Open your price list and pick three products. Compute margin as profit ÷ price. Does it match the percentage you think you are earning?
- Find the formula in your pricing spreadsheet. If it says cost × 1.25 anywhere near a "25% margin" label, you have found money.
- Reprice using cost ÷ (1 − target margin) and see how far off your current prices are.
- Before any discount, compute the required breakeven volume: old profit per unit ÷ new profit per unit. If the answer is 1.5 and you expect a 20% lift, skip the promotion.
Margin and markup are separated by one denominator and, routinely, thousands of dollars. Know which one your spreadsheet speaks, translate deliberately, and the "mystery" of vanishing profits usually stops being a mystery the same afternoon.