How to use the Compound Interest Calculator tool
3 simple steps · under a minute
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Enter your starting amount
Type the money you start with, and how much you will add each month.
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Set rate, time and compounding
Enter the yearly interest rate, number of years and how often interest is compounded.
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Watch it grow
See the final balance, total deposits and interest earned, with a year-by-year chart.
About Compound interest calculator
Compound interest means you earn interest on your interest. Each period, the interest is added to your balance, and the next period’s interest is calculated on the bigger amount. Over many years, this snowball effect can grow your savings far beyond what you put in.
This calculator shows the effect clearly. Enter a starting amount, a monthly deposit, an interest rate and a number of years, and see your final balance split into what you deposited and what you earned. Try adding a few years — time is the most powerful part of compounding.
Monthly contributions
Include regular deposits, the way most people actually save and invest.
Any compounding frequency
Daily, monthly, quarterly, half-yearly or yearly compounding.
Growth chart and table
See how deposits and interest build up, year by year.
Frequently asked questions
What is the compound interest formula?
A = P(1 + r/n)^(nt), where P is the starting amount, r the annual rate, n the number of compounding periods per year and t the number of years. Regular deposits are added on top of this.
What is the difference between simple and compound interest?
Simple interest is paid only on the original amount. Compound interest is paid on the original amount plus the interest already earned, so it grows faster.
How often is interest compounded?
It depends on the account. Savings accounts often compound daily or monthly, while some bonds and deposits compound yearly. More frequent compounding earns slightly more.
What is the Rule of 72?
Divide 72 by the annual interest rate to estimate how many years it takes to double your money. At 8%, money doubles in about 9 years.
Is this financial advice?
No. Returns on real investments vary and are not guaranteed. Use the results as an illustration for planning.