Compound Interest Calculator
Calculate compound interest with optional monthly contributions. Enter your principal, annual rate, investment period, and compounding frequency to see your final balance, total interest earned, and a year-by-year growth chart.
Final Balance
$37,405
Total Interest
$15,405
Total Contributions
$22,000
How it works
This compound interest calculator runs entirely in your browser — no data is sent to any server. Simply fill in the fields above and the result updates instantly. You can copy the output with the copy button provided.
Frequently Asked Questions
What is compound interest?
Compound interest is interest calculated on both the initial principal and the accumulated interest from previous periods. It grows exponentially over time.
How often should interest compound?
More frequent compounding means slightly higher returns. Daily compounding yields the most, but the difference vs. monthly is small. Most savings accounts and investment products compound monthly.
What is the Rule of 72?
Divide 72 by your annual interest rate to estimate how many years it takes to double your money. At 6%, your money doubles in about 12 years.
Does this calculator include monthly contributions?
Yes. You can add a monthly contribution amount to simulate regular savings deposits on top of your initial principal.