Compound Interest Calculator
Calculate compound interest on savings, investments, and deposits. See how your money grows with monthly contributions and different compounding frequencies.
Enter investment details to calculate growth
Free Compound Interest Calculator – See How Your Money Grows
Our free compound interest calculator shows you exactly how your money can grow over time through the power of compound interest. Whether you're planning for retirement, saving for a down payment, or building an emergency fund, this tool helps you visualize your financial future.
Enter your initial investment, monthly contributions, interest rate, and time period to see your future balance, total interest earned, and year-by-year growth.
The Compound Interest Formula
A = P(1 + r/n)^(nt)
- A = Future value (final amount)
- P = Principal (initial investment)
- r = Annual interest rate (as decimal)
- n = Number of times compounded per year
- t = Time in years
The Power of Compound Interest
Divide 72 by your interest rate to estimate doubling time. At 7%, money doubles in ~10 years.
Starting 10 years earlier can mean 2-3x more money at retirement due to compounding.
Frequently Asked Questions
What is compound interest?
Compound interest is "interest on interest." Unlike simple interest (calculated only on principal), compound interest calculates interest on both the principal and previously earned interest.
How often should interest compound?
More frequent compounding (daily vs. annually) yields slightly higher returns. However, the difference is usually small. Monthly compounding is common for savings accounts.
What's a realistic interest rate?
Savings accounts: 4-5% (2024). Stock market average: 7-10% historically. CDs: 4-5%. Always consider inflation (2-3%) for real returns.
How much should I invest monthly?
A common guideline is to save 15-20% of income for retirement. Even $100/month at 7% for 30 years grows to over $120,000.
What's the difference between APR and APY?
APR (Annual Percentage Rate) is the base rate. APY (Annual Percentage Yield) includes compound interest, showing actual yearly return.