The profit margin formula
Profit Margin = (Revenue − Cost) ÷ Revenue × 100. It expresses profit as a share of revenue, so a $60 cost sold for $100 is a 40% margin.
Margin vs. markup
Margin is profit over price; markup is profit over cost. The same dollar profit always shows a lower margin than markup — a distinction that trips up a lot of candidates. This tool shows both.
Margins in case interviews
Pricing and profitability cases live and die on margin math. Being fluent here lets you reason about price changes and cost cuts without reaching for a calculator.