Compound Interest Calculator
Project savings growth with compounding and regular contributions.
Frequently asked questions
How does compound interest work?
Compound interest earns returns on both your original balance and the interest already earned, so the balance grows faster over time than with simple interest.
What does this calculator estimate?
It projects the future value of savings from an initial amount, regular monthly contributions, an annual interest rate and how often interest compounds.
What is the difference between simple and compound interest?
Simple interest is figured only on the original principal, while compound interest is figured on the principal plus accumulated interest, which accelerates growth.
How do monthly contributions change the result?
Adding money each month increases the balance that earns interest, so consistent contributions can grow the final value substantially over many years.
Why does compounding frequency matter?
More frequent compounding, such as monthly versus yearly, applies interest more often, which slightly increases the total return for the same annual rate.
What is the rule of 72?
It is a quick estimate that dividing 72 by the annual percentage rate gives roughly the number of years for money to double.
Does a longer time horizon help?
Yes. Because growth compounds, leaving money invested longer generally produces disproportionately larger balances, which is why starting early matters.
Is this financial advice?
No. The result is a general estimate that assumes a constant rate and is not a guarantee of returns or financial advice.