Return on investment is one of those metrics everyone uses and almost everyone applies incorrectly at least part of the time. The formula is simple; the interpretation is where most people go wrong. A complete ROI calculation tells you not just how much you made but how efficiently your capital was deployed — and whether you'd have done better putting the money elsewhere.
What changed in 2026
- Higher interest rates raised the opportunity cost baseline. A 4–5% risk-free rate from Treasuries means any investment's ROI needs to beat that to be worth the added risk.
- Tax treatment became harder to ignore. With capital gains rates unchanged but brackets adjusted, after-tax ROI now differs more meaningfully from pre-tax ROI depending on holding period.
- Real estate ROI calculations got more complex as financing costs rose; many investors underestimated the true cost of capital when rates were low.
The basic formula
ROI = (Net Gain ÷ Cost of Investment) × 100
Where:
- Net Gain = Final Value − Initial Cost
- Cost of Investment = everything you put in (purchase price + fees + any additional capital)
Example: You buy 10 shares of a stock at $50/share ($500 total) and sell at $65/share ($650). Your broker charges $5 in total commissions.
- Net Gain = $650 − $500 − $5 = $145
- ROI = ($145 ÷ $505) × 100 = 28.7%
Annualized ROI: the version that matters for comparisons
Simple ROI says nothing about how long the money was tied up. Annualized ROI (also called compound annual growth rate, CAGR) accounts for time:
Annualized ROI = [(1 + ROI)^(1/n) − 1] × 100
Where n = number of years.
| Investment |
Simple ROI |
Holding period |
Annualized ROI |
| Stock A |
50% |
2 years |
~22.5% |
| Stock B |
50% |
8 years |
~5.2% |
| Real estate |
80% |
5 years |
~12.5% |
| Savings account |
20% |
4 years |
~4.7% |
Stock A and B both returned 50% total — but annualized, Stock A nearly outperformed Stock B by 4× per year. Always annualize when comparing investments held for different periods.
What to include in "cost"
Many ROI calculations undercount costs. Include:
- Purchase price (obvious)
- Transaction fees and commissions
- Taxes on gains (especially short-term vs. long-term rates)
- Ongoing costs — for real estate: mortgage interest, property taxes, insurance, maintenance, vacancy
- Inflation adjustment — optional but useful for long-term comparisons
Real estate example: A rental property bought for $250,000, with $10,000 closing costs, $15,000 in repairs over 3 years, and sold for $320,000 after agent commissions, generates:
- Net Gain ≈ $320,000 − $250,000 − $10,000 − $15,000 = $45,000
- ROI = ($45,000 ÷ $275,000) × 100 ≈ 16.4% over 3 years (~5.2% annualized)
How to calculate ROI step by step
- Identify total investment cost — everything you spent to acquire and maintain the asset.
- Determine the final value — sale proceeds net of transaction costs.
- Apply the basic formula: (Net Gain ÷ Total Cost) × 100.
- Annualize it if comparing to other investments.
- Adjust for taxes if you want after-tax ROI (divide net gain by your marginal or capital gains rate as applicable).
ROI vs. other return metrics
| Metric |
What it captures |
When to use |
| Simple ROI |
Total return, no time |
Quick snapshots |
| Annualized ROI / CAGR |
Time-adjusted compound return |
Comparing multi-year investments |
| IRR (Internal Rate of Return) |
Cash flows at different times |
Real estate with rental income, businesses |
| Net Present Value (NPV) |
Absolute dollar value created |
Capital budgeting decisions |
For stock investments, annualized ROI is usually sufficient. For real estate or business investments with cash flows at multiple points, IRR is more accurate.
Common mistakes
Ignoring ongoing costs. A rental property ROI calculated without maintenance, vacancy, and property taxes will always look better than the real number.
Comparing simple ROI across different time horizons. A 30% return in 6 months versus a 30% return over 3 years are completely different outcomes.
Excluding taxes. Capital gains taxes reduce real returns significantly, especially for short-term investments. If you're comparing assets, compare after-tax.
Treating sunk costs as "already paid." If you renovated before selling and the renovation didn't add value, it is still part of your cost basis.
What to skip
- ROI calculations that exclude transaction costs — commissions, closing costs, and fees add up and can shift a "good" investment to average.
- Nominal ROI comparisons over long periods without inflation adjustment — a 100% return over 20 years in a high-inflation environment may represent flat real purchasing power.
- ROI as the only metric for risk decisions — a 30% ROI with a 50% chance of total loss is very different from a 10% ROI with near certainty.
FAQ
What is a "good" ROI?
Context-dependent. The S&P 500 historical average is roughly 7–10% annualized after inflation. Real estate averages 8–12% total return including rental income and appreciation. Any investment ROI should be compared to what you would have earned in the next-best option at comparable risk.
How is ROI different from profit margin?
Profit margin measures how much of revenue converts to profit (for businesses). ROI measures return relative to what was invested. They are related but different metrics.
Can ROI be negative?
Yes — if you lost money on an investment, ROI is negative. A −20% ROI means you lost 20 cents for every dollar invested.
What is the difference between ROI and CAGR?
CAGR (compound annual growth rate) is specifically the annualized version of ROI that assumes compounding. They are the same concept; CAGR is more precise for multi-year periods.
Where to go next
See How to value a stock in 2026, How to invest in ETFs in 2026, and How to build a 3-fund portfolio in 2026.