Identify the ROI period (e.g., monthly, quarterly, annually)
Determine total investment (all costs during the period)
Determine total returns (all benefits during the period)
Calculate net profit: total returns − total investment
Calculate ROI: (net profit ÷ total investment) × 100
If using multiple investments, compute ROI per investment or use total investment/total returns combined
If returns occur over time, use the ROI period that matches the cash flows included
For costs that occur over time, include them in total investment for the same period as returns
Use consistent units (cash vs. accrual) across both returns and investment
Record results as a percentage (or keep as a decimal if preferred)