Compound Interest Calculator
See how your money grows over time with the power of compound interest. Includes monthly contributions and multiple compounding frequencies.
Future Value
$37,405
Total Contributed
$22,000
Interest Earned
$15,405
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What is a Compound Interest Calculator?
Compound interest is the process by which interest is earned not only on the original principal but also on the accumulated interest from previous periods. Albert Einstein reportedly called it the "eighth wonder of the world" — it is the fundamental mechanism behind long-term wealth building.
The formula for compound interest is: A = P(1 + r/n)^(nt), where A is the final amount, P is the principal, r is the annual interest rate, n is the number of compounding periods per year, and t is the number of years. This calculator also supports regular monthly contributions, which dramatically accelerate growth.
The difference between starting to invest at age 25 versus age 35 can be enormous. Investing $500/month from age 25 to 65 at 7% annual return yields approximately $1.2 million. Starting at 35 yields only about $567,000 — less than half, despite only a 10-year difference.
How to Use the Compound Interest Calculator
See exactly how your savings or investment will grow over time.
- 1
Enter your initial investment
Input the starting amount you are investing or saving today.
- 2
Enter the annual interest rate
Use the expected annual return rate. The S&P 500 has historically averaged about 10% before inflation.
- 3
Set the time period
Enter the number of years you plan to invest.
- 4
Add monthly contributions (optional)
Enter any regular monthly amount you plan to add to the investment.
- 5
Choose compounding frequency
Select how often interest compounds — daily, monthly, quarterly, or annually.
- 6
View your growth chart
The calculator shows your final balance, total contributions, and total interest earned, along with a year-by-year growth chart.
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