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Last updated: October 20, 2026 · Tax year 2026

Investment return calculator

Enter what you have now, how much you add each month, how many years you will invest and the yearly return you want to test. You get the estimated future value, how much of it is your own money and how much is growth.

This is an illustration, not a forecast or financial advice. Returns are not guaranteed, they vary every year, and you can lose money. Taxes, fees and inflation are not included.

Example

Start with $5,000, add $300 a month for 20 years at a steady 7% a year: about $176,472. You would have put in $77,000, so about $99,472 comes from growth. Keep going for 30 years and it is about $406,574 on $113,000 put in.

What $0 plus a monthly amount grows to in 20 years

Monthly4% a year6% a year8% a year10% a year
$100$36,677$46,204$58,902$75,937
$300$110,032$138,612$176,706$227,811
$500$183,387$231,020$294,510$379,684
$1,000$366,775$462,041$589,020$759,369

Starting from zero, contributions added at the end of each month, monthly compounding.

How the calculation works

  1. Monthly rate = yearly return ÷ 12.
  2. Each month: balance = balance × (1 + monthly rate) + monthly contribution.
  3. Repeat for years × 12 months. Total put in = starting amount + monthly contribution × months. Growth = balance − total put in.

Yearly returns in real markets are uneven. A plan that averages 7% can have years of losses along the way, so the order of returns matters if you withdraw money.

Frequently asked questions

How is the future value worked out?

Each month the balance grows by one twelfth of the yearly return, then your monthly contribution is added at the end of that month. That repeats for every month of the plan, which is monthly compounding.

What return should I enter?

There is no safe number. Stocks have returned more than savings accounts over long periods but with big swings, and nobody can promise a future rate. Try a low, a middle and a high figure and look at the range, not a single answer.

Does this include taxes, fees or inflation?

No. Fund fees, taxes on gains and rising prices all lower what you keep and what the money can buy. A 7% return with 2% inflation is closer to 5% in buying power.

Is it better to start early or invest more later?

Time matters a lot because growth is earned on earlier growth. In the example above, the same $300 a month for 30 years ends far above 20 years, even though only 10 more years of deposits were added.

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