Free Compound Interest Calculator
Compound interest is the effect of earning (or paying) interest on top of previously accrued interest. Over long periods it dwarfs simple interest — this calculator quantifies both the maturity value and the year-by-year growth path.
Results
Growth over 10 years
Disclaimer: This calculator provides estimates only and does not constitute financial advice. Actual loan terms may vary by lender.
About the Compound Interest Calculator
The formula
A = P × (1 + R/n)^(nt), where P is principal, R is annual rate (decimal), n is compounding frequency per year (1 annual, 4 quarterly, 12 monthly) and t is time in years. Compound Interest = A − P.
Why compounding frequency matters
The more frequent the compounding, the higher the effective yield. $10,000 at 10% for 10 years is $25,937 annually compounded, $26,850 quarterly, $27,070 monthly. Small on year one, meaningful by year ten.
The rule of 72
A quick sanity check: money doubles in roughly 72 ÷ interest rate years. At 8% compound, money doubles in about 9 years. Use this to spot-check the calculator's output.
Frequently asked questions
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