Compound Interest Calculator
Project the future value of your investments with compound interest and regular contributions. Results update instantly as you type.
Your details
Future value
How to use this calculator
Enter your starting balance and monthly contribution.
Set your interest rate, years to grow, and compound frequency.
Read the future value and the split between contributions and interest.
Understanding your results
Compound interest means your interest earns interest. Each compounding period — monthly, quarterly, or annually — adds the earned interest to your principal, so the next period earns on a larger base. The longer your money stays invested and the more frequently it compounds, the steeper the growth curve becomes. This is why starting early matters far more than the amount you contribute. To see how regular deposits accelerate this effect, use the savings calculator. If you're comparing a lump-sum investment against recurring contributions, the loan calculator shows how borrowing costs compound in the opposite direction.
What factors affect your growth
Interest rate
A higher rate compounds faster and grows your balance more.
Contribution
Regular contributions are the biggest driver of long-term growth.
Time
More years let compounding do its most powerful work.
Worked examples
20-year growth
$10,000 to start, $200 per month at 7.00%
Grows past $115,000
Start early
The same plan over 30 years
Compounding adds tens of thousands more
Frequently asked questions
What is compound interest?
It is interest earned on both your original money and the interest already added, which makes your balance grow faster over time.
How is the future value calculated?
We compound your starting balance and each monthly contribution at your chosen frequency, then subtract any tax on the interest.
Why does a higher frequency grow faster?
More frequent compounding means interest is added sooner and starts earning its own interest earlier.
What happens if I contribute more?
Increase the monthly contribution and the projection updates immediately to show the long-term difference.
Is the result guaranteed?
No. CalcPilot gives planning estimates only; check with your bank for actual rates and terms.
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Disclaimer
CalcPilot's calculations are estimates for planning purposes only. They are not financial, legal, or tax advice. Consult a qualified professional before acting on any result.