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Compound Interest Calculator

Compound interest means your money earns interest, and then that interest earns interest of its own. The longer you leave it alone, the faster it grows. Enter your numbers to watch it happen. New to the idea? How compound interest works explains it with a snowball, and why starting early wins.

Advanced settingsAnnually

Once interest is added, it starts earning interest too, so adding it more often grows your balance a little faster. Savings accounts often add it daily or monthly. Money you put in starts earning the next time interest is added.

No rate is guaranteed, so see what happens if yours turns out lower or higher. With a 7% rate, 2 shows 5%, 7%, and 9%. Leave it at 0 to see just your rate.

Ending balance

$13,913.65

You put in

$11,000.00

Interest earned

$2,913.65

The same math runs in reverse on debt: a credit card balance you don't pay off grows the same way. See how compound interest works against you.

How it works

The calculator starts with $5,000, adds $100 a month, and grows it at 7% a year for 5 years. You put in $11,000, interest adds $2,913.65, and you end with $13,913.65. Change any of the four numbers to see your own.

Interest is added once a year on what was in the account at the start of that year, so each year's monthly amounts start earning the following year. That's the same method as the SEC's compound interest calculator at Investor.gov (opens in a new tab), so your results match theirs.

Under Advanced settings:

  • How often interest is added: once a year, twice a year, quarterly, monthly, or daily. Adding it more often grows the balance a little faster, because each bit of interest starts earning sooner. Savings accounts usually add interest monthly or daily.
  • A rate range (±): shows what you'd end with at a lower and a higher rate too. Real returns change from year to year, so a range is more honest than a single number.

Copy link to these numbers saves your inputs in the address, so you can bookmark a plan or share it.

What rate should you use?

The rate is the part you can't know for sure. A savings account's rate is set by the bank and can change at any time; stock market returns swing a lot from year to year and are only steadier over long stretches. Try a cautious rate and a hopeful one with the rate range, and see what rate will you actually get? for where real rates come from. This is a planning tool, not a promise or financial advice.

How long until your money doubles? Divide 72 by the rate: at 7%, about 10 years (the Rule of 72).