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Compound Interest Calculator
See how an investment or savings balance grows with compound interest and regular contributions over time.
$
$
%
yr
Future balance
$144,573
You put in $58,000+$86,573 interest
What this does
Enter a starting amount, interest rate and time period to see how compound interest grows your balance. Add a regular monthly contribution to model a savings plan, and see how much of the final total is your own money versus earned interest.
How to use it
- 1Enter your starting balance and an optional monthly contribution.
- 2Set the annual interest rate and how often it compounds.
- 3Choose the number of years and read the projected final balance.
Examples
- $10,000 at 7% for 20 years grows to about $38,697
- Adding $200/month makes a large difference over time
Frequently asked questions
- What is compound interest?
- Compound interest is interest earned on both your original balance and the interest already added. Because each period's interest earns its own interest, balances grow faster over time — the core reason long-term investing is powerful.
- How does compounding frequency affect growth?
- More frequent compounding (monthly or daily vs annually) earns slightly more, because interest is added to the balance sooner and starts earning on itself. The difference is modest but real over long periods.
- What is APY?
- APY (annual percentage yield) is the effective yearly return once compounding is included. A 6% rate compounded monthly has an APY of about 6.17%, which is why APY is the fairer way to compare savings accounts.