Compound Interest Calculator
See how the power of compound interest grows your money over time. Enter your initial investment, expected return rate, and monthly contributions to instantly visualize your wealth trajectory. This free compound interest calculator supports multiple compounding frequencies, inflation adjustment, and detailed year-by-year breakdowns so you can plan your financial future with confidence. No signup required.
Calculate Your Investment Growth
Regular Contributions
When contributions are added during each period
Your Future Value
$0.00
Principal
$10,000.00
Contributions
$120K
Interest
$214K
Interest is 62.2% of your total balance
Rule of 72
At 8.0% interest, your money doubles in approximately 9.0 years.
Milestones Reached
Investment Growth Chart
Final Value Breakdown
Year-by-Year Breakdown
See how your actual investments compare to these projections. Track real returns, income, and expenses all in one place with Auritrack.
Try Auritrack FreeHow to Calculate Compound Interest
Enter Your Initial Investment Amount
Type your starting principal in the Initial Investment field. This is the lump sum you are investing today. Use the slider or type directly for precision.
Set the Expected Annual Return Rate
Enter the annual interest rate or expected return percentage. For stock market investments, 7-10% is a common historical average. Savings accounts typically offer 1-5%.
Choose Your Investment Time Horizon
Set the number of years you plan to keep the money invested. Longer time horizons benefit dramatically more from compounding due to exponential growth.
Add Regular Monthly Contributions
If you plan to invest additional money regularly, enter the amount and frequency under Regular Contributions. Even small monthly contributions compound significantly over decades.
View Your Projected Growth and Charts
See your projected future value, growth chart, and year-by-year breakdown instantly. Toggle inflation adjustment to see real returns in today's purchasing power.
How Compound Interest Grows Your Money
The Power of Compounding
Compound interest is often called the eighth wonder of the world, and for good reason. Unlike simple interest, which only earns returns on your original investment, compound interest earns returns on your returns. This creates an exponential growth curve that accelerates dramatically over time. A $10,000 investment at 8% annual interest grows to $21,589 in 10 years with simple interest, but to $21,911 with monthly compounding. Over 30 years, the gap becomes enormous: $34,000 with simple interest versus $100,627 with compound interest.
FV = P × (1 + r/n)n×t
Where P = principal, r = annual rate (decimal), n = compounding periods per year, t = years
Why Starting Early Matters
Time is the most critical variable in compound interest. An investor who starts at age 25 with $200 per month at 8% will have approximately $702,000 by age 65. Someone who starts at age 35 with the same contributions will have only $298,000 — less than half, despite only missing 10 years. The first investor contributed $96,000, while the second contributed $72,000. The $24,000 difference in contributions produced over $400,000 more in wealth, illustrating why every year of delay has a compounding cost.
Compounding Frequency Explained
How often interest compounds affects your final balance. Daily compounding earns slightly more than monthly, which earns more than quarterly or annually, because interest begins earning its own interest sooner. For a $10,000 deposit at 8% over 20 years: annual compounding yields $46,610; monthly compounding yields $49,268; and daily compounding yields $49,530. While the difference between daily and monthly compounding is marginal for most practical purposes, the gap between annual and more frequent compounding is meaningful over long horizons.
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Frequently Asked Questions
Disclaimer: This tool is provided for informational and educational purposes only. It does not constitute financial, tax, investment, or legal advice. Results are estimates based on the inputs you provide and may not reflect actual financial outcomes. Always consult a qualified financial professional before making financial decisions.