How this investment return calculator works
In Project returns mode, enter your starting amount, monthly contribution, expected annual return and time horizon. The calculator grows your portfolio month by month — contributions are added and the monthly return (annual rate ÷ 12) is applied to the balance. The benchmark panel shows what the same contributions would become at 5%, 7% and 10% annual returns.
In Calculate CAGR mode, enter a starting value, a target ending value and the number of years. The calculator uses the CAGR formula to find the exact annual return rate required to get from one to the other.
What is CAGR?
CAGR (Compound Annual Growth Rate) is the single annual return that would turn an initial value into a final value over a given number of years, as if growth were perfectly smooth each year. The formula is:
The Rule of 72
A quick mental shortcut: divide 72 by the annual return to estimate how many years it takes to double your money. At 7% you double in roughly 10 years; at 10% about 7 years; at 6% about 12 years. For savings with compound interest, see the compound interest calculator.
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Building savings toward a specific goal? Try the savings goal calculator. Comparing paying off debt vs investing? Use the compound interest calculator. Wondering whether to buy or keep renting? See the rent vs buy calculator.
Frequently asked questions
- What is CAGR?
- Compound Annual Growth Rate — the steady annual return that maps an initial value to a final value over time, ignoring year-to-year volatility.
- What is the average stock market return?
- The S&P 500 has historically returned ~10% nominally and ~7% in real (inflation-adjusted) terms over long periods.
- How does compound growth work?
- Returns compound — gains earn further gains. At 7%, $10,000 grows to over $76,000 in 30 years without adding a cent.
- Is this calculator free?
- Yes — free, no sign-up, runs entirely in your browser.