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Financial Calculator Suite

Select a calculator below. All calculations are performed locally — no data is transmitted.

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Compound Interest

Initial investment or deposit

Expected annual return rate

More frequent = slightly higher returns

Enter values and click Calculate

Your growth chart and year-by-year table will appear here.

How Compound Interest Works

Compound interest is calculated using the formula: FV = P × (1 + r/n)^(n×t), where P is principal, r is the annual rate (as a decimal), n is the number of compounding periods per year, and t is time in years.

The key insight is that you earn interest on your interest. With monthly compounding at 7%, your effective annual rate (EAR) is actually 7.229% — slightly higher than the nominal 7%. Over 30 years, this small difference compounds into thousands of additional dollars.

Daily compounding produces the highest final balance because interest is added to the principal 365 times per year rather than once. However, the difference between daily and monthly compounding is smaller than most people expect — the biggest factor is always the rate and time horizon, not the compounding frequency. Starting early is far more impactful than optimizing compounding intervals.

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