The Mathematics of ROI
The basic formula for Simple ROI is:
The Annualized ROI Formula
To find the geometric mean of your return (Annualized ROI), we use:
Where n is the number of years the investment was held. This formula reveals the "Compound Annual Growth Rate" (CAGR).
Why ROI Alone Isn't Enough
While ROI is powerful, it has three major blind spots:
- Risk: A high-ROI investment (like a startup) usually carries a much higher risk of total loss than a lower-ROI investment (like a treasury bond).
- Liquidity: A 15% ROI on a stock you can sell in seconds is often better than a 15% ROI on a house that takes 6 months to sell.
- Inflation: If your ROI is 5% but inflation is 6%, you have actually lost "Real" purchasing power.
Standard ROI Benchmarks:
- • Stock Market (Index): 7% - 10% (Annualized)
- • Real Estate: 3% - 6% (Appreciation) + Rental Yield
- • Savings Account: 0% - 5% (Depending on interest rates)
- • Venture Capital: 25%+ (Target, but high failure rate)
ROI vs. ROE
In business and real estate, Return on Equity (ROE) is often more important. If you buy a $1M house with $200k of your own money (leverage), and the house value goes up 10%, your ROI is 10%, but your ROE is 50%. Leverage acts as a massive multiplier on your personal capital's efficiency.
How to Use This Tool
For the most accurate results, ensure you subtract all costs from your "Amount Returned." For a stock trade, this includes sell-side commissions and any taxes you will owe on the gain. For real estate, subtract closing costs and agent fees.