Article — ROI Calculator
ROI calculator: measure return on investment
Return on investment (ROI) is the net gain or loss on an investment expressed as a percentage of the amount invested. For a $10,000 investment that ends at $13,500, ROI equals 35%; if that took three years, the annualized rate (CAGR) is 10.52%.
The metric is universal because it strips out absolute dollar amounts. A $1,000 gain on $5,000 invested is twice as good as a $1,000 gain on $10,000 invested, even though the dollar figure looks identical. ROI lets you compare a stock trade, a rental property, and a small business on the same scale.
What is ROI?
ROI answers a single question: for every dollar I put in, how many cents came back as profit? A 25% ROI means you got 25 cents of profit per dollar invested. The number can be positive (gain) or negative (loss), and it has no unit beyond the percent sign.
The Securities and Exchange Commission emphasizes that ROI is descriptive, not predictive. Past returns do not commit a stock, fund, or business to repeating them. The SEC requires mutual fund prospectuses to display 1-, 5-, and 10-year returns precisely because no single window tells the whole story.
The Federal Reserve's long-run inflation target of 2% is the implicit floor for a meaningful real ROI. Anything below 2% nominal is losing purchasing power even when the headline number is positive.
Simple ROI vs annualized ROI
Simple ROI ignores time. Annualized ROI (CAGR) converts a multi-year return into the equivalent steady annual rate. The two diverge fast as holding periods grow.
Doubling your money over 10 years is a 100% simple ROI but only 7.18% per year compounded. Doubling it in two years is also 100% simple ROI, but the annualized figure is 41.42% — almost six times as fast. Without annualizing, you cannot fairly compare investments held for different durations.
+100% over 10 yr = 7.18% CAGR+100% over 5 yr = 14.87% CAGR+100% over 2 yr = 41.42% CAGR+50% over 5 yr = 8.45% CAGRThe ROI formula
Two formulas cover almost every case. Simple ROI is gain divided by initial investment, expressed as a percent. Annualized ROI takes the nth root of the growth factor and subtracts one.
- Simple ROI = ((Final Value − Initial) / Initial) × 100
- Annualized ROI (CAGR) = (Final / Initial)^(1/years) − 1
- Final value from ROI = Initial × (1 + ROI)
- Doubling time ≈ 72 / annual rate (Rule of 72)
- Exact doubling = ln(2) / ln(1 + rate)
What counts as a good ROI
The default benchmark is the broad US stock market. The S&P 500 has averaged roughly 10% nominal CAGR over rolling 30-year windows, per Federal Reserve Economic Data and Robert Shiller's long-run dataset. Adjusted for inflation tracked by the Bureau of Labor Statistics, the real return is closer to 7%.
Anything materially above 10% per year sustained over a decade is above-market. Anything below the 10-year Treasury yield — currently in the 4-5% range per Federal Reserve H.15 data — is below the risk-free rate, which means you are taking risk without being compensated for it.
ROI vs IRR, NPV, and CAGR
ROI is the simplest member of a family of return metrics. Each adds something the others miss.
CAGR is just annualized ROI — same math, different name when used for multi-year horizons. Internal rate of return (IRR) handles irregular cash flows, like a rental property with monthly rent plus a sale at year ten. Net present value (NPV) discounts future cash flows back to today using a chosen discount rate, giving an absolute dollar figure rather than a percentage.
For a single buy-and-sell investment with no cash flows in between, ROI and CAGR are sufficient. For projects with deposits, withdrawals, or income payouts, IRR is the better tool.
Common ROI mistakes
A 60% return over six years sounds better than 30% over two years, but the annualized rates are 8.15% versus 14.02%. The shorter window wins handily. Always convert to CAGR before comparing.
Other frequent errors: quoting gross ROI without subtracting fees and taxes, treating last year's S&P return as a forecast, and confusing total dollar gain with percent return. A $100 gain on $200 invested is a 50% ROI; a $100 gain on $10,000 is 1%.
Always net out taxes when comparing investments held in taxable accounts to ones held in retirement accounts. Long-term US capital gains rates are 0%, 15%, or 20% depending on income; short-term gains hit ordinary income tax brackets.
Real ROI after inflation
Nominal ROI is the headline number; real ROI subtracts the loss of purchasing power. The BLS Consumer Price Index has averaged around 2-3% annually over long windows, with sharper spikes during shocks.
A 10% nominal CAGR during a year of 3% inflation produces roughly 6.8% real return via the Fisher equation: (1 + nominal) / (1 + inflation) − 1. Over decades, the gap compounds; a portfolio that earns 10% nominally for 30 years grows 17.4×, but in inflation-adjusted dollars it grows closer to 7.6×.
Why the order of returns matters
Two investors can have the same average return and end up with different portfolio values if they are adding to or drawing from the account. This is called sequence-of-returns risk and it dominates retirement planning research.
If you retire just before a bear market and start drawing income, the early drawdown shrinks your base permanently. The same average return delivered in the opposite order — gains first, drawdown later — preserves far more wealth. The takeaway: average ROI is necessary but not sufficient. Volatility patterns and timing matter, especially near retirement.
Per Federal Reserve studies on household wealth, the median 65-year-old US household holds far less in retirement accounts than a steady 10% CAGR would predict. Sequence risk, contribution gaps, and fee drag account for most of the shortfall.
This calculator handles the most common case — a single starting amount and a single ending value over a fixed period. For investments with cash flows in between (a rental property collecting rent, a business with monthly profits, a stock paying dividends), internal rate of return is the more accurate tool. Treat ROI as a quick comparison metric and IRR or NPV as the final-decision metric for complex projects.
One last note on real-world usage: brokerage statements and fund prospectuses report ROI in many flavors — total return, time-weighted return, money-weighted return — each with different methodology. The SEC has standardized which methodology funds must use in advertising, but individual portfolio reports may differ. When comparing two return figures, always check whether both are computed the same way before drawing conclusions.