Compound Interest Calculator
Estimate how savings can grow with compound interest and regular monthly contributions.
About the Compound Interest Calculator
Compound interest can make savings grow because returns are added to the balance and can themselves earn returns. This calculator also models regular monthly contributions.
How to use this calculator
- Enter your starting balance.
- Enter a monthly contribution.
- Enter an annual interest rate and time period.
- Choose how often interest compounds and review the projected value.
How the calculation works
The calculator compounds the starting balance and recurring contributions at the selected frequency. It then separates the projected ending balance into contributions and estimated interest.
Example
Starting with $10,000, adding $300 each month, and assuming a 7% annual rate for 10 years illustrates how regular contributions and compounding can work together.
Things to keep in mind
- The assumed rate is not guaranteed.
- Fees and taxes can reduce real-world returns.
- Small changes in the rate or time horizon can have a large effect over long periods.
- Use multiple scenarios rather than relying on one projection.
Frequently asked questions
What is compound interest?
It is interest calculated on the original balance plus previously accumulated interest.
Do monthly contributions matter?
Yes. Regular contributions add new money that can also participate in future growth.
Is the projected result guaranteed?
No. It is a mathematical projection based on the rate you enter.