Marketing ROI measures the revenue gain from a campaign relative to its cost. The formula is: ROI = ((Revenue − Cost) / Cost) × 100%. For example, if a Google Ads campaign costs $2,000 and generates $8,000 in revenue, the ROI is ((8,000 − 2,000) / 2,000) × 100 = 300%. A positive ROI means the campaign is profitable; a negative ROI means the costs exceed the returns. Our calculator also shows absolute net profit alongside the percentage, giving you both views needed for budget allocation decisions.