Compound Interest Calculator— Free & Private
Calculate how investments grow over time with compound interest.
Final Amount
$325,159.17
All calculations happen in your browser. No data stored.
What Is Compound Interest?
A compound interest calculator shows how your money grows when you earn interest on both your initial principal and the accumulated interest from previous periods. Unlike simple interest, which only applies to the original amount, compound interest causes your savings to grow exponentially over time. Enter your starting amount, contribution schedule, interest rate, and compounding frequency to see projected growth. All processing happens in your browser.
How to Use Compound Interest Calculator
Enter principal amount
Input the starting balance or initial investment amount.
Set rate and term
Enter the annual interest rate and the number of years you plan to invest.
Add contributions
Optionally add regular monthly or annual contributions.
View growth projections
Review the final balance, total interest earned, and a year-by-year growth chart.
Why Use Our Compound Interest Calculator?
Frequently Asked Questions
What is the difference between compound and simple interest?
Simple interest is calculated only on the original principal. Compound interest is calculated on the principal plus all previously accumulated interest, leading to faster growth over time.
How often should interest be compounded for the best return?
More frequent compounding (daily vs. annually) produces slightly higher returns. However, the difference narrows significantly at higher compounding frequencies.
Does this calculator account for taxes or inflation?
The calculator shows nominal growth before taxes and inflation. For real returns, subtract your expected tax rate and inflation rate from the interest rate.