ROI (Return on Investment) is calculated as: (net profit - investment) / investment x 100. Unlike ROAS, which measures gross revenue, ROI accounts for all costs (ad budget, management, creative production, etc.) and net profit. It is the ultimate success metric for any marketing investment.
Total investment: EUR 3,000 (EUR 2K ads + EUR 1K management). Revenue generated: EUR 13,000. Net profit (30% margin): EUR 3,900. ROI = (3,900 - 3,000) / 3,000 x 100 = 30%.