Compound Interest Calculator

See how your savings or investments could grow with regular contributions and compound interest.

What is compound interest?

Compound interest means you earn returns not only on the money you put in, but also on the returns you've already earned. Over time, this snowball effect can make growth accelerate, which is why starting early matters so much.

How this calculator works

It assumes your return compounds monthly and that you add your contribution at the end of each month. Real investment returns vary from year to year and can be negative, so treat the result as an estimate, not a promise.

Ways to make compounding work harder

• Start as early as possible: time is the most powerful input.
• Contribute consistently: automate monthly deposits.
• Keep fees low: high fees reduce what compounds. See our beginner's guide to index funds.
• Avoid withdrawing early, so growth can keep building on itself.

This calculator provides hypothetical estimates for educational purposes only. It isn't investment advice, and actual returns aren't guaranteed.