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Investment Calculator

Project how an investment could grow. Enter what you start with, what you add each month, the yearly return you expect and how long you will stay invested. The result is shown both in future dollars and adjusted for inflation, with a year-by-year table.

Quick examples
$
$
%
years
%

Used only for the “in today’s dollars” figure. Set to 0 to ignore.

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Future value$300,850.72
Total contributed
$130,000.00
Investment growth
$170,850.72
In today’s dollars
$183,600.45
What the balance is made of
  • Contributions
  • Growth
Growth year by year
YearContributedGrowthBalance

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    Your recent calculations

    Results you calculate here are kept on this device so you can come back to them.

      Formula

      Monthly return i = annual return ÷ 12
      Future value = start × (1 + i)^m + contribution × ((1 + i)^m − 1) ÷ i, where m is the number of months
      In today’s dollars = future value ÷ (1 + inflation)^years

      How to use it

      1. Enter your starting balance and monthly contribution.
      2. Enter an expected annual return and the number of years.
      3. Set inflation to see what the final balance would buy in today’s money.

      Worked examples

      $10,000 plus $500 a month at 7% for 20 years, with 2.5% inflation

      Future value
      $300,850.72
      Total contributed
      $130,000.00
      Investment growth
      $170,850.72
      In today’s dollars
      $183,600.45

      $250 a month from zero at 8% for 30 years

      Future value
      $372,589.86
      Total contributed
      $90,000.00
      Investment growth
      $282,589.86
      In today’s dollars
      $372,589.86

      Choosing a return

      Over the long run US stocks have returned roughly 10% a year before inflation and about 7% after it; bonds and cash have returned much less. A diversified portfolio is often modeled at 5–7%. Fund fees come straight off the return, so enter the figure after costs.

      Real markets do not deliver a smooth rate. The same average return can leave you with very different balances depending on the order of good and bad years, so treat the output as a midpoint, not a promise. This is an estimate, not financial advice.

      Questions people ask

      How much will $500 a month be worth in 20 years?

      Starting with $10,000 and earning 7% a year, $300,850.72: $130,000 contributed and $170,850.72 of growth. In today’s dollars at 2.5% inflation that is $183,600.45.

      How much will $500 a month be worth in 30 years?

      From zero at 7%, $609,985.50. The first 10 years only produce $86,542.40; most of the growth comes late.

      What does $250 a month grow to at 8%?

      $372,589.86 after 30 years, from $90,000 of contributions.

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