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Compound Interest Calculator
Calculate compound interest on savings or investments. See how your money grows with monthly contributions.
Compound Interest — The Power of Exponential Growth
Compound interest is the addition of interest to the principal sum, so that interest earns interest. Albert Einstein reportedly called it "the eighth wonder of the world."
Formula
A = P × (1 + r/n)^(n×t) where: P=principal, r=annual rate, n=compounding frequency, t=years
Example
$10,000 at 7% for 30 years = $76,123. Adding $200/month = $243,994
💡 Useful Tips
Start as early as possible — every year of delay is costly.
Small, consistent monthly contributions beat a large lump sum later.
Compare funds by real return (after fees and inflation).
What is the difference between simple and compound interest?
Simple interest is calculated only on the principal. Compound interest is calculated on principal plus accumulated interest — creating exponential growth.
What compounding frequency is best?
More frequent compounding = slightly more growth. Daily beats monthly, but the difference is smaller than you might expect.