Details: This calculator estimates how an initial amount may grow with compound interest over time. You can also add a monthly contribution to see the combined effect of saving and compounding.
Use it for savings, investing, retirement planning, or comparing how small differences in annual return can change long-term results.
Calculate compound interest
amount
%/year
years
amount
If you are not sure, monthly compounding is a reasonable default for simulation.
Enter your numbers to calculate.
Future value0
Total contributions0
Growth from interest0
Growth vs contributions0%
Money growth chart
Total contributionsTotal value
The explanation will appear after you enter your numbers.
Year
Total contributions
Growth
Total value
What is compound interest?
Compound interest means your interest or investment return is added back to your balance, so the next period can earn returns on both your original money and previous growth.
In simple words, growth may feel slow at first, but it can become stronger as the balance gets larger over time.
Easy examples
Example 1 Start with 100,000, earn an average return of 5% per year, and leave it for 20 years. The calculator estimates the future value and the growth from interest.
Example 2 Start with 50,000 and add 5,000 each month for 15 years. The calculator shows how much came from your own contributions and how much came from compounding.
Good to know
This is an estimate based on the annual return you enter. It is not a guaranteed result. Real investment returns can change because of market conditions, risk, taxes, fees, and timing.
If you use this for a savings account, check the bank interest rate, compounding method, tax rules, and account terms.