A Markup is Profit divided by the Cost as a percentage. A Margin is Profit divided by the Sale Price or Revenue as a percentage. For example, let's say you sold a product for $10 that only cost you $5. Your markup would be (Sales Price $10 - Cost $5) / Cost $5 = 1 or 100% markup. Your margin would be (Sales Price $10 - Cost $5) / Sales Price $10 = 0.5 or 50% Profit Margin. Therefore, you marked up your product 100% and sold it for a 50% Profit Margin.