Compound Interest Calculator

How to use: Enter what you have saved now, what you add each month, the yearly return you expect and the number of years.

What is compound interest?

Compound interest means you earn returns on your original money and on the returns you already earned. That snowball effect is why starting early often matters more than investing a large amount later. This compound interest calculator compounds monthly and adds your deposit at the end of each month.

Example

Start with $5,000, add $300 a month and earn 7% a year for 20 years. You would put in $77,000 in total and end up with about $176,000, which means roughly $99,000 came from growth rather than your own deposits.

Why the result is only an estimate

Investments do not earn a steady return every year. Stock markets rise and fall, and fees and inflation reduce what your money can buy. Try a few rates, such as 4%, 7% and 10%, to see a range instead of a single number. For a savings account, use the account’s actual interest rate.

Frequently asked questions

How often does interest compound?

This calculator compounds monthly. Savings accounts often compound daily or monthly, and the difference in the final balance is usually small.

What matters more, time or deposits?

Both help, but time has a bigger effect than most people expect. Try changing the years from 20 to 30 and compare the growth earned.

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Estimates for education only, not financial advice.