Compound interest Calculator

With additional monthly contributions

Use this calculator to find out how much a given savings rate will grow your long term net worth.

  1. Starting amount is the amount you already have saved in an interest-bearing account or investment.
  2. Additional Monthly Investment is just that: how much more will you contribute each month. (If you plan to contribute one lump-sum bonus each year, just divide that bonus by 12 to get the monthly amount.)
  3. What is the interest/growth rate that you expect for this account or investment? Use your bank account’s interest rate, or use the percentage you think the investment will grow per year. For reference, the generally accepted rate for the stock market as a whole is 7%, adjusted for inflation (It’s closer to 10% without adjusting, but you can’t ignore inflation, especially when looking at long time frames)
  4.  Number of years: How long will you continue to add the monthly additions, and commit to not withdrawing anything?

This is a very simplified way of getting a ballpark idea of how much you need to save per month to reach your goals. No one can predict the stock market; even very long term average returns are subject to variation. And we’re completely ignoring that you will probably get raises and hopefully continue to increase your monthly contributions over time. But still, it can be quite an eye-opener to realize the potential growth available to you!

NOTE: Don't use commas or dollar-signs in your numbers. Only use digits (and decimal points if needed). Type 100000, not $100,000. Sorry, I'm still learning javascript and haven't figured out how to fix that, yet!