Compound Interest Calculator
See how savings grow with compound interest and regular contributions.
Frequently Asked Questions
How is compound interest calculated?
The future value uses A = P(1 + r/n)^(nt) plus the future value of your monthly contributions, where P is the principal, r the annual rate, n the number of compounding periods per year and t the years.
Why does compounding frequency matter?
Interest is added more often with monthly or daily compounding, so each interest payment starts earning interest sooner. Over long periods the difference between annual and monthly compounding becomes significant.
Do contributions compound too?
Yes. Each monthly contribution is invested from the month it is made and compounds for the remaining time, which is why starting contributions early matters so much.
Is the Compound Interest Calculator free, and is my data private?
Yes. It is completely free and every calculation runs locally in your browser, so the numbers and dates you enter are never uploaded, stored, or shared with anyone.
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