Compound Interest Calculator
Compound interest calculator
Compound interest earns interest on your principal and on the interest already added, so savings grow faster over time. Enter a starting amount, rate, and time below — add a monthly contribution to see the difference regular saving makes.
Final balance
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You contributed
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Interest earned
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In one line
Frequently asked questions
What is compound interest?
Interest earned on both your principal and the interest already added — so savings grow faster than simple interest over time.
How is it calculated?
A = P × (1 + r/n)^(n×t), with regular contributions added each period. P is principal, r annual rate, n compounds/year, t years.
Does frequent compounding earn more?
Yes, slightly — monthly or daily beats yearly at the same rate because interest is added sooner.
Estimates only, assuming a constant rate. Not financial advice.