Compound Interest Calculator
See how regular saving and compounding grow your money over time.
Results
- Future value
- Total contributions
- Total interest earned
Compound interest means earning interest on your interest: each period’s earnings are added to the balance and earn returns of their own. Over long periods this snowball effect is powerful, which is why starting early matters so much.
This calculator includes regular monthly contributions and lets you choose how often interest compounds — annually, quarterly, monthly or daily — then shows your balance year by year.
How to calculate Compound interest
- Enter your initial deposit.
- Enter how much you will add each month (or 0).
- Enter the expected annual interest rate or return and the number of years.
- Choose the compounding frequency.
Compound interest formula
Future value = P × (1 + r/n)^(n·t)With contributions: each month Balance = Balance × (1 + monthly rate) + Contribution
Compound interest example
Starting with $10,000, adding $500 a month at 7% compounded monthly, you would have about $106,600 after 10 years — of which $70,000 is your own money.
Compound interest: common questions
What is the difference between simple and compound interest?
Simple interest is earned only on the principal. Compound interest is also earned on previously earned interest.
What is the Rule of 72?
Divide 72 by the annual rate to estimate how many years it takes to double your money. At 8%, money doubles in about 9 years.
How do I account for inflation?
Enter an approximate real rate (nominal rate − inflation) to see your result in today’s purchasing power.