Profit margin calculator
Margin is the share of the sale price that is profit. It is the number that tells you whether your sourcing is actually working.
Margin vs markup — the classic mix-up
Buy for $10 and sell for $20 and you have a 100% markup but a 50% margin. Markup is measured against your cost; margin is measured against the sale price. Both are shown above because both are useful, but they answer different questions: markup tells you how you price, margin tells you what share of every incoming dollar you keep.
The mistake that quietly loses money is aiming for a markup number while your costs creep. A flat "double my money" rule means your margin is stuck at 50% before fees, shipping supplies, and returns — which can leave less than you think once everything real is subtracted.
This calculator deliberately ignores platform fees so it works for any way of selling. If you want the after-fee number for a specific marketplace, the platform calculators on this site include them.
Questions
What counts as my cost?
Everything it took to get the item ready to sell: purchase price, and ideally your share of mileage, cleaning, repairs, and packaging. Most people only count the purchase price, which makes margins look better than they are.
What is a good margin for reselling?
There is no universal number — a 30% margin on items that sell in a week can beat an 80% margin on items that sit for a year. Judge margin together with how fast the item actually sells.
Why do my margin and markup percentages differ?
Because they divide the same profit by different bases. Profit divided by sale price is margin; profit divided by cost is markup. Markup is always the larger number when you are profitable.