Enter a starting amount, rate, years, compounding frequency, and an optional regular contribution. You get the future value plus a year-by-year (or period-by-period) growth table.

The power of compounding

Compound interest is interest earned on both your original money and on the interest it has already earned. That feedback loop is why money grows slowly at first and then accelerates, and why starting early matters far more than starting with a large amount.

Two levers drive the result: time and rate, with time usually the stronger of the two. Compounding more often, monthly rather than yearly, adds a little extra, but the dramatic differences come from leaving money invested for decades. This calculator shows the future value and how much of it is pure interest.

The formula

Without contributions: A = P x (1 + r/n) ^ (n x t) With contributions, each period: balance = balance x (1 + r/n) + contribution

Worked example

1,000 at 5% compounded monthly for 10 years grows to about 1,647. Add 200 a month and it grows to over 32,000, and the table shows exactly how it builds each year.

How to read your result

Compound interest earns interest on previous interest, so growth accelerates over time. More frequent compounding and longer time horizons both increase the final amount, with time being the most powerful lever. The progression table shows contributions, interest, and balance for each year or period.

Frequently asked questions

What does compounding frequency change?
More frequent compounding earns slightly more, because interest starts earning interest sooner. You can choose annually, semi-annually, quarterly, monthly, or daily.
Can I add regular deposits?
Yes. Enter a contribution per period and the growth table shows how each deposit and its interest build the balance over time.
How is this different from simple interest?
Simple interest is paid only on the original principal; compound interest is paid on principal plus accumulated interest.

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