Compounding view
Compound Interest Calculator
See how your money grows with compound interest and regular contributions. This page is for checking whether time, rate, and deposit discipline actually support the story you are telling yourself.
For an official plain-language explainer, read Investor.gov on compound interest.
How Compound Interest Works
Compound interest calculates interest on both the initial principal and the accumulated interest from previous periods. Combined with regular monthly contributions, it demonstrates the powerful effect of compounding over time. The calculator supports different compounding frequencies to show how more frequent compounding accelerates growth.
Formula
A = P(1 + r/n)^(nt) + PMT * [((1 + r/n)^(nt) - 1) / (r/n)]
Key Features
- ✓Calculate compound interest on initial principal
- ✓Include regular monthly contributions
- ✓Choose compounding frequency: daily, monthly, quarterly, or annually
- ✓See total interest earned vs total contributions
Pro Tip
Start investing as early as possible. Thanks to compound interest, even small monthly contributions can grow dramatically over decades. The difference between starting at 25 vs 35 can mean hundreds of thousands of dollars by retirement.
What compounding actually does
Compounding is simple math, not magic. The effect only becomes obvious once the time horizon is long enough for interest to earn interest several times over.
Worked example
$10,000 invested at 7 percent with $250 monthly contributions grows to about $102,000 in 20 years. The same return without the monthly contribution is much lower, which is why deposit discipline matters.
Practical caveats
Ignore taxes, fees, and market volatility at your peril. A projection can be useful without being a forecast, but it only works if you treat the return as an assumption rather than a promise.
What to do next
If you want to compare growth paths, move to Investment Return Calculator. If you are comparing growth against borrowing cost, check Loan Calculator.
Formula
Future value = principal × (1 + rate / compounding periods) ^ periods
Add contributions and the curve changes quickly. A modest monthly deposit often matters more than a small change in the annual rate.
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