ROI Calculator for Personal Investments: Stocks, Real Estate & Side Projects

September 5, 2026 · 5 min read

Every investment decision comes down to one question: what return will I get for my money and time? Whether you are evaluating a stock portfolio, a rental property, a side business, or even a course or certification, ROI gives you a clear number to compare options.

Simple ROI vs Annualized ROI

Simple ROI tells you the total return: you invested $10,000 and now have $15,000, so your ROI is 50%. But over what period? Annualized ROI (CAGR) accounts for time. A 50% return over 5 years is 8.45% per year. A 50% return over 2 years is 22.5% per year. Always compare investments on annualized terms.

Real Estate ROI

Rental property ROI includes rental income, appreciation, tax benefits, and mortgage paydown — minus expenses like maintenance, property taxes, insurance, and management. Cash-on-cash return measures income relative to your down payment, not the full property value. A property with 8% cash-on-cash return on a $50,000 down payment generates $4,000 per year in cash flow.

Stock Market ROI

The S&P 500 has returned roughly 10% annually over the long term (7% after inflation). Individual stocks vary dramatically. When calculating your stock portfolio ROI, include dividends — they account for about 2% of total S&P 500 returns historically. Do not forget to subtract trading fees and tax implications.

Side Project ROI

For side businesses, include your time as a cost. If you spend 10 hours per week on a side project earning $500 per month, your effective hourly rate is about $12.50. If your day job pays $40/hour, the financial ROI is negative unless the project scales. Factor in learning value, enjoyment, and future potential alongside pure financial return.

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Our free ROI Calculator handles this instantly — no signup, no limits.

Also useful: our Compound Interest Calculator for related calculations.