Compound Interest Calculator
Calculate future value, total contributions, and estimated interest earned from compound growth.
How this calculator works
How to use this calculator
Enter your starting amount, monthly contribution, annual interest rate, and time period. Choose how often interest is compounded, then click Calculate Compound Interest.
Formula used
For a single starting amount, compound interest is commonly calculated as A = P(1 + r/n)^(nt), where P is the principal, r is the annual interest rate, n is the number of compounding periods per year, and t is time in years. This calculator also adds monthly contributions and compounds the balance month by month.
Example calculation
If you start with $1,000, add $100 per month, earn 6% per year, and invest for 10 years, the estimated future value is about $17,908.48. Total contributions are $13,000, so estimated interest earned is about $4,908.48.
What the result means
The future value is an estimate of how much your balance could grow if the rate and contributions stay constant. Actual investment returns can change and are not guaranteed.
Frequently asked questions
Does this include taxes or fees?
No. This calculator does not include taxes, inflation, account fees, or investment risk.
Can the interest rate be negative?
The calculator accepts negative rates, but negative rates reduce the balance over time.
Is this financial advice?
No. This is an educational estimate only. Speak with a qualified professional before making financial decisions.