How to use the investment return calculator
- Choose Find my return if you know what the investment is worth now, or Project growth to see what it could become at a return you pick.
- Enter the Starting amount and, if you added money regularly, the Monthly contribution.
- Enter the Ending value (or the Expected annual return) and the Years invested. Decimals work, so 18 months is 1.5.
- Read the annualized return, total return and gain, compare them with stocks, bonds and cash, and open the Year-by-year table for the detail.
How the return is calculated
Total return (ROI) is your gain divided by the money you put in. The annualized return, or compound annual growth rate (CAGR), is the steady yearly rate that turns the starting amount into the ending value:
CAGR = (ending value ÷ starting amount)1 ÷ years − 1
This matches the average annual total return formula the SEC's Form N-1A sets for mutual funds. When you add money every month, your deposits are not profit, so the calculator finds the one monthly rate that grows the starting amount plus each deposit (made at the end of each month) to the ending value, then converts it to a yearly rate. That is a money-weighted return, the same idea as an internal rate of return. Project growth uses the monthly equivalent of your annual rate, so a lump sum grows by exactly that rate each year.
Worked example
The calculator opens with $10,000 that grew to $25,000 over 10 years, with no monthly contributions. The total gain is $15,000.00, a total return of +150.00%, and the CAGR is (25,000 ÷ 10,000)1 ÷ 10 − 1 = +9.60% a year. Dividing 150% by 10 gives a simple 15.00% a year, which overstates the result because later years grow on earlier gains. At the long-run stock average of 10.0%, the same $10,000 would have reached $25,937.42.
Limits and edge cases
- Results are before taxes, fund fees and inflation. Subtract your fund's expense ratio from the annualized return for a rough net figure, and use the inflation calculator to see the ending value in today's dollars.
- Contributions are treated as equal deposits at the end of every month. Irregular deposits or withdrawals need a spreadsheet XIRR function.
- Long-run averages hide big swings from year to year, and they are not a forecast.
- To rank several investments side by side, use the ROI calculator. For a savings account with daily or monthly compounding, use the compound interest calculator.
Frequently asked questions
What is a good annual return on an investment?
From 1928 to 2025, US stocks (the S&P 500 with dividends) returned about 10.0% a year compounded, 10-year Treasury bonds about 4.5%, and 3-month Treasury bills about 3.4%, before inflation. A return that beats inflation and fits the risk you took is a reasonable target.
What is the difference between ROI and annualized return?
ROI is the total gain as a percentage of what you invested, over the whole period. Annualized return (CAGR) spreads that gain into an equal yearly rate, so investments held for different lengths of time can be compared.
Why is my CAGR lower than my total return divided by the years?
Because growth compounds. A steady 9.60% a year turns $10,000 into $25,000 in 10 years, since each year grows on the gains before it. Dividing the 150% total return by 10 ignores that and gives 15%.
How do monthly contributions change my return?
Money you add is not profit. The calculator takes every deposit out of the gain and weights each one by how long it was invested, so a balance built mostly from deposits does not look like a high return.
Sources: NYU Stern (Aswath Damodaran), Historical Returns on Stocks, Bonds and Bills, 1928 to 2025; SEC Form N-1A (average annual total return). Estimates only, not investment advice.