Direct answer
Compound interest is interest calculated on the initial principal as well as accumulated interest from prior periods, generating exponential wealth growth over time.
How to use this tool
Enter Principal Balance
Input your initial investment amount in your local currency.
Configure Interest Rate & Frequency
Specify annual interest rate and select compounding frequency (monthly, quarterly, annually).
Set Duration & Contributions
Choose investment horizon in years and optional periodic contribution amounts.
Inspect Curve & Export CSV
View dynamic balance growth and download full amortization schedule directly to your device.
How Compound Interest Works & Mathematical Formula
The standard compound interest formula models asset growth over discrete intervals: A is final accumulated balance, P is initial principal, r is annual nominal interest rate in decimal form, n is compounding frequency per year, and t is investment duration in years.
- More frequent compounding produces slightly higher effective annual yield (APY).
- Consistent periodic contributions substantially accelerate the exponential compounding curve.
Practical examples
$10,000 at 7% Annual Return for 10 Years
Input: Principal: $10,000, Rate: 7%, Duration: 10 years, Compounding: Monthly, Contributions: $0
Output: Total Balance: $20,096.61, Total Interest Earned: $10,096.61
Without adding further principal, the investment doubles over a ten-year horizon under monthly compounding.
Limitations
- Does not factor in variable tax rates, capital gains taxes, or inflation adjustments.
- Assumes a constant fixed nominal interest rate over the entire investment duration.
Frequently asked questions
What is the difference between APR and APY?
APR (Annual Percentage Rate) reflects the simple annual nominal rate without compounding, whereas APY (Annual Percentage Yield) reflects the true annual return taking compounding frequency into account.
Is my financial data uploaded to any server?
No. FreeKitX operates entirely client-side. Your financial figures, calculations, and generated CSV exports are processed in your browser and never leave your device.
Authoritative References & Standards
- SEC Investor.gov Compound Interest Guidance ↗ — Official U.S. government educational guidance on compounding calculations.
- Investopedia Compound Interest Formula Guide ↗ — Reference guide on discrete and continuous compounding mechanics.