Compound Interest Calculator
See how your money grows over time with the power of compounding. Add regular contributions for a complete picture.
Initial Investment
$
%
yr
$
FUTURE VALUE
$0
Invested
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Interest Earned
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Return
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GROWTH CHART
Year-by-Year Breakdown
| Year | Balance | Interest | Contributions |
|---|
* This is a projection assuming a constant rate of return. Actual investment returns vary and are not guaranteed.
Compound Interest Formula
A = P(1 + r/n)^(nt), where A = future value, P = principal, r = annual rate, n = compounding frequency, t = years. With monthly contributions: add PMT × ((1 + r/n)^(nt) − 1) / (r/n).
Q. How powerful is compound interest?
$10,000 at 7% for 30 years = $76,122 without contributions. Add $200/month and it becomes $243,994 — the "eighth wonder of the world" as Einstein reportedly called it.
Q. What is the Rule of 72?
Divide 72 by your interest rate to estimate how many years it takes to double your money. At 7%: 72 ÷ 7 ≈ 10.3 years to double. At 10%: 7.2 years.