Compound Interest Calculator
See how your money grows with compound interest over time.
Your investment will grow to $3,165,947.35, earning $3,035,947.35 in compound interest on top of your $130,000.00 in contributions.
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Growth Over Time
What is Compound Interest Calculator?
Compound interest is the concept of earning interest on both your initial principal and the accumulated interest from previous periods. This creates exponential growth over time — often called "the eighth wonder of the world." The power of compounding means that even small, regular contributions can grow into substantial sums when given enough time. This calculator helps you visualize how your money can grow with regular monthly contributions.
How to Interpret Your Results
The Rule of 72 is a quick way to estimate how long it takes to double your money: divide 72 by your annual return rate. At 7% annual return, your money doubles approximately every 10 years. Starting early is crucial — even a few extra years of compounding can make a substantial difference in your final balance.
How to Use This Compound Interest Calculator
Simply adjust the input fields on the left using sliders or by typing values directly. Results update instantly in real-time — no button required. You can share your exact calculation by clicking Share Link.
Formula
Where A = future value, P = principal, r = annual rate, n = compounds/year, t = years, PMT = contribution.
Frequently Asked Questions
What is compound interest?
Compound interest is interest calculated on both the initial principal and the accumulated interest from previous periods.
How often does interest compound?
Monthly is most common for savings accounts and investments. Our calculator defaults to monthly compounding (12x/year).
What is the Rule of 72?
Divide 72 by your annual interest rate to estimate how many years it takes to double your investment. At 7%, ~10 years.