Profit margin calculator

Knowing your profit margin is essential for every marketplace seller. Whether you sell on OnBuy or another platform, your margin tells you how much money you actually keep from every sale after accounting for product cost, marketplace fees, and delivery charges. A healthy margin means your business is sustainable; a thin or negative margin is a warning sign that pricing needs to change.

Profit margin vs markup — these are often confused but measure different things. Margin is your profit expressed as a percentage of the selling price, while markup is your profit as a percentage of your cost. For example, buying a product for £10 and selling it for £20 gives you a 50% margin but a 100% markup. Understanding both numbers helps you set prices that are competitive yet profitable.

Marketplace fees can eat into margins quickly. OnBuy charges a category-based commission on each sale, and delivery costs add another layer. The calculator above factors in both, so you can see the real profit on every item before you list it. Many sellers discover they are losing money on certain products only after running the numbers properly.

Once you know your margins, the next step is protecting them while staying competitive. Re-Pricer automates this process: it monitors competitor prices and adjusts your listings in real time, ensuring you never drop below your minimum margin. Instead of manually recalculating after every competitor change, let Re-Pricer handle it while you focus on growing your business.