In short: Compound Interest Calculator projects how savings or investments grow over time with a starting amount, monthly contributions and compound interest.
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How to use Compound Interest Calculator
3 quick steps. Most people are done in under a minute.
- 1
Enter a starting amount and monthly contribution.
- 2
Set the interest rate, years and compounding frequency.
- 3
See your final balance and growth year by year.
Compound Interest Calculator features
- Starting amount plus monthly contributions
- Yearly, quarterly, monthly or daily compounding
- Growth chart split into contributions and interest
- Year-by-year table and rule-of-72 doubling time
When to use Compound Interest Calculator
- Plan retirement or long-term savings goals
- See the effect of starting to invest earlier
- Compare savings accounts with different rates
About this tool
Project the future value of your savings or investments with a starting amount, monthly contributions, interest rate and compounding frequency. A year-by-year chart and table show how much comes from your deposits versus interest.
Compound Interest Calculator FAQ
What is compound interest?
Compound interest is interest earned on both your deposits and the interest already added, so your balance grows faster over time than with simple interest.
What formula does this use?
For a single deposit, A = P × (1 + r/n)^(n × t). With monthly contributions, the calculator simulates each month, adding interest at the effective monthly rate and then your deposit.
How long does it take to double my money?
A quick estimate is the rule of 72: divide 72 by the annual interest rate. At 8%, money roughly doubles every 9 years.
Are the results guaranteed?
No. They assume a constant rate with no taxes or fees. Real investment returns go up and down, so this is for illustration only and isn’t financial advice.