SellculateMargin and markup describe the same dollar of profit from two different directions, and mixing them up is probably the most common pricing mistake in small business. It doesn't feel like a mistake when it happens — the arithmetic looks right, the spreadsheet balances, and the price goes live. The damage only shows up later, as a margin that's consistently thinner than the one you thought you set.
The two definitions
Margin (more precisely, gross margin) is profit as a percentage of the selling price:
margin = (price − cost) ÷ price
Markup is profit as a percentage of the cost:
markup = (price − cost) ÷ cost
Take an item that costs $20 and sells for $50. Profit is $30 either way. But margin is 30 ÷ 50 = 60%, while markup is 30 ÷ 20 = 150%. Same sale, same profit, wildly different percentages — because the denominators are different.
Two consequences follow from the definitions. First, for any profitable sale, markup is always the larger number, since cost is smaller than price. Second, margin can never reach 100% (that would mean the item cost nothing), while markup can climb without limit.
Why the confusion costs real money
The classic failure looks like this. A seller decides they want "40% profit" on a product that costs $12. They multiply: 12 × 1.40 = $16.80, and list it at that price. But check what that price actually delivers: profit is $4.80, and margin is 4.80 ÷ 16.80 = 28.6% — not 40%. They applied a 40% markup while intending a 40% margin.
To genuinely earn a 40% margin on a $12 cost, you divide instead of multiply:
price = cost ÷ (1 − margin) = 12 ÷ 0.60 = $20.00
At $20, profit is $8 and margin is exactly 40%. The difference between $16.80 and $20.00 is 16% of revenue given away — on every unit, forever, without ever showing up as an error anywhere. Multiplied across a catalog, this single mix-up quietly decides whether a business is comfortable or barely breaking even.
The mistake also runs the other direction: a buyer negotiating wholesale terms who hears "we work on a 50% margin" and mentally files it as "50% markup" will misjudge the seller's economics by a wide amount, as the table below shows.
The conversion table
Margin and markup convert into each other with two small formulas:
margin = markup ÷ (1 + markup)markup = margin ÷ (1 − margin)
Some common pairs (percentages expressed as decimals in the formulas above):
| Markup | Equivalent margin |
|---|---|
| 25% | 20% |
| 50% | 33.3% |
| 100% | 50% |
| 150% | 60% |
| 300% | 75% |
Notice how the gap widens as the numbers grow. At low percentages the two are close enough that a mix-up stings but doesn't sink you; a 25% markup versus a 25% margin is a 5-point error. At the levels common in retail and handmade goods — keystone pricing is a 100% markup — the gap is enormous.
Which one should you use?
Both, for different jobs.
- Use margin to judge the business. Margin is a share of revenue, so it lines up with how accountants, marketplaces and financial statements slice the world. Questions like "can this product absorb a 10% fee and a 15% discount?" are margin questions, because fees and discounts are also percentages of price.
- Use markup to set prices from cost. When you're standing at a supplier's table or costing a recipe of components, cost is the number in front of you, and "cost times X" is the natural move. That's fine — as long as you know what margin the markup translates to.
The discipline that prevents every version of this mistake is simple: never state a percentage without its denominator. "40% — of price or of cost?" is a one-second question that has saved a great deal of money.
Margin after fees: the number that actually matters
One more wrinkle. The margin in these formulas is computed from cost and price alone — but for anyone selling through a marketplace or taking card payments, the spendable number is what's left after platform commission, payment processing, shipping and packaging. A product with a textbook 60% margin can land in your account with far less once the fee stack has taken its share. That's a big enough topic that we cover it separately in pricing around marketplace fees, and the reverse-solving version — starting from the margin you want and deriving the price — in the reverse margin guide.
Where Sellculate fits in
Sellculate sidesteps the margin-vs-markup trap by showing both at once: enter cost and price and you see profit, margin and markup instantly, labeled and side by side. Working from a target instead? Enter cost plus a target margin and the app solves for the selling price — the divide-not-multiply math handled for you — or enter price plus a target margin to find the maximum cost you can pay. It's a local-first Android app with no account system and no analytics SDK.
This guide is general information about pricing arithmetic, not tax, legal, or financial advice.