Compound Interest Calculator
Calculate compound interest with monthly contributions. See your investment grow year by year with an interactive growth chart and amortization schedule.
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What Is Compound Interest?
Compound interest is interest calculated on both the initial principal and the accumulated interest from previous periods, creating exponential growth over time.
Formula
A = P(1 + r/n)^(nt) + PMT × ((1 + r/n)^(nt) − 1) / (r/n)Example
Investing $10,000 at 7% compounded monthly with $200/month contributions for 10 years yields $63,879 — $34,000 in contributions and $29,879 in interest.
Frequently Asked Questions
What is compound interest?
Interest earned on both your original deposit and previously earned interest, creating a snowball effect over time.
How does compounding frequency affect returns?
More frequent compounding yields slightly higher returns. Monthly vs annual compounding can add 0.5-1% extra over long periods.
What's the Rule of 72?
Divide 72 by your annual interest rate to estimate years to double your money. At 7%, money doubles in ~10.3 years.