Compound Interest Calculator
Compound interest is the quiet engine behind most lasting wealth. Your money earns a return, then that return starts earning returns of its own, and the growth curve bends upward the longer you leave it alone. Move the sliders below to watch your own numbers play out.
$134,270 after 20 years. $73,270 of that is growth your money earned on its own.
Worked examples
Real results from this calculator, computed for a few common scenarios. Move the sliders above to run your own numbers.
| Starting amount = $20,000 | $211,006 after 20 years. $131,006 of that is growth your money earned on its own. |
| Starting amount = $50,000 | $332,169 after 20 years. $222,169 of that is growth your money earned on its own. |
| Starting amount = $80,000 | $453,331 after 20 years. $313,331 of that is growth your money earned on its own. |
Popular scenarios, precomputed
One-click answers to the versions of this question people ask most.
Saving $100 a Month for 10 Years: What It Grows To
Saving $100 a Month for 20 Years: What It Grows To
Saving $100 a Month for 30 Years: What It Grows To
Saving $100 a Month for 40 Years: What It Grows To
Saving $200 a Month for 10 Years: What It Grows To
Saving $200 a Month for 20 Years: What It Grows To
Saving $200 a Month for 30 Years: What It Grows To
Saving $200 a Month for 40 Years: What It Grows To
Saving $300 a Month for 10 Years: What It Grows To
Saving $300 a Month for 20 Years: What It Grows To
Saving $300 a Month for 30 Years: What It Grows To
Saving $300 a Month for 40 Years: What It Grows To
Saving $500 a Month for 10 Years: What It Grows To
Saving $500 a Month for 20 Years: What It Grows To
Saving $500 a Month for 30 Years: What It Grows To
Saving $500 a Month for 40 Years: What It Grows To
Saving $1,000 a Month for 10 Years: What It Grows To
Saving $1,000 a Month for 20 Years: What It Grows To
Saving $1,000 a Month for 30 Years: What It Grows To
Saving $1,000 a Month for 40 Years: What It Grows To
What Will $1,000 Be Worth in 10 Years If You Invest It?
What Will $1,000 Be Worth in 20 Years If You Invest It?
What Will $1,000 Be Worth in 30 Years If You Invest It?
What Will $5,000 Be Worth in 10 Years If You Invest It?
What Will $5,000 Be Worth in 20 Years If You Invest It?
What Will $5,000 Be Worth in 30 Years If You Invest It?
What Will $10,000 Be Worth in 10 Years If You Invest It?
What Will $10,000 Be Worth in 20 Years If You Invest It?
What Will $10,000 Be Worth in 30 Years If You Invest It?
What Will $25,000 Be Worth in 10 Years If You Invest It?
What Will $25,000 Be Worth in 20 Years If You Invest It?
What Will $25,000 Be Worth in 30 Years If You Invest It?
What Will $50,000 Be Worth in 10 Years If You Invest It?
What Will $50,000 Be Worth in 20 Years If You Invest It?
What Will $50,000 Be Worth in 30 Years If You Invest It?
What Will $100,000 Be Worth in 10 Years If You Invest It?
What Will $100,000 Be Worth in 20 Years If You Invest It?
What Will $100,000 Be Worth in 30 Years If You Invest It?
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How this math works
The calculator starts with your opening balance and walks forward one month at a time. Each month it multiplies your balance by one twelfth of your annual return, then adds your monthly contribution. Repeating that simple step hundreds of times produces the curve you see in the chart.
The gap between the two lines is the part your money earned on its own. Early on the gap looks small and unimpressive. Give it fifteen or twenty years and the earnings often grow larger than everything you put in, which is exactly why starting early matters more than starting big.
Common questions
What rate of return should I use?
A long run figure of 6 to 8 percent is a common planning assumption for a diversified stock portfolio, which is why the slider defaults to 7. Use something lower, such as 4 or 5 percent, if your money sits in bonds or savings accounts.
Does this account for taxes or inflation?
No. The chart shows raw growth before taxes and inflation. For a rough inflation adjusted view, subtract about 3 percentage points from your expected return and run it again.
How is interest compounded in this tool?
Monthly. Your annual rate is divided by twelve and applied every month, with contributions added at the end of each month. Most real world accounts compound monthly or daily, so the results will be very close.
Put this calculator on your website
Bloggers, teachers, credit unions, HR teams: embed the live Compound Interest Calculator free. Copy the snippet below — the tool keeps working and stays up to date automatically, no maintenance on your side.
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