Start early
Each extra year gives your money more time to compound.
Compound Interest Calculator
Find out what your savings or investment could grow to. Add a starting amount, regular monthly contributions and an expected return, and see the growth year by year.
- 100% free
- No sign-up
- Runs in your browser
Future value0
Total contributed0
Interest earned0
How to use
How to use the Compound Interest Calculator
- Enter your starting amount.
- Add a monthly contribution, or leave it at 0.
- Enter the annual interest rate or expected return.
- Choose the number of years and compounding frequency.
- See the future value, the chart and the yearly breakdown.
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About this tool
How does compound interest work?
With compound interest you earn interest not only on the money you put in, but also on the interest it has already earned. Over short periods the effect is small. Over ten, twenty or thirty years it becomes the biggest part of the balance.
The two things that matter most are time and consistency. Starting a few years earlier often matters more than investing a larger amount later, and regular monthly contributions keep the snowball growing. The chart shows how much of your final balance came from your own deposits and how much from growth.
Good to know
Making compounding work for you
Contribute regularly
Small, steady monthly deposits often beat occasional large ones.
Use realistic rates
Returns are not guaranteed. Try a cautious, a middle and an optimistic rate to see the range.
Remember inflation and fees
A 2% yearly fee or high inflation can take a big bite out of long-term growth.
FAQ
Compound Interest Calculator FAQs
What is the compound interest formula?
Without contributions it is A = P(1 + r/n)nt, where P is the principal, r the annual rate, n the compounding periods per year and t the number of years.
When are monthly contributions added?
At the end of each month, before that month's interest is applied.
Does compounding frequency make a big difference?
Monthly compounding earns a little more than yearly at the same rate, but the rate and the time invested matter far more.
Is this financial advice?
No. It is an educational calculator. Speak to a licensed adviser before making investment decisions.
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