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Compound Interest Calculator

Watch your savings grow — like Ollie collecting pebbles, one month at a time.

Compound interest FAQ

How does compound interest work?

Compound interest means you earn interest on your interest. Each month, interest is added to your balance, and the next month you earn interest on the larger amount.

How often is interest compounded here?

This calculator compounds monthly, which is the standard for savings accounts and most investment projections.

Is the 7% rate realistic?

7% is a common long-term average for diversified stock market returns, but past performance never guarantees future results.

Can I include monthly contributions?

Yes. Enter a monthly contribution to see how regular saving dramatically boosts your final amount.

What is the formula used?

FV = P(1 + r/n)^(nt) + PMT × [((1 + r/n)^(nt) − 1) / (r/n)], with monthly compounding (n = 12).

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