Compound Interest Calculator
A compound interest calculator. Enter your initial amount, monthly deposit, annual return, and period to instantly see how much it grows with compound interest. See how principal and gains split and how it snowballs year by year.
What is the Compound Interest Calculator?
Enter your initial amount, monthly deposit, annual return, and period, and it instantly shows the final value, how much you actually contributed, and how much of the total came from compound growth.
For plans where you keep adding money over a long time — savings accounts, retirement funds, or regular ETF investing — you can picture how much your money could grow over the years.
Why compounding is powerful — interest earns interest
Simple interest is paid only on your principal, but compound interest is paid on your principal plus the interest already earned. The longer the period, the faster it snowballs.
The key levers are the return rate and time. Time matters most, so starting early makes a dramatic difference.
How to use it
Nudge the monthly deposit up or down and compare how different the total looks after 20–30 years.
Switch the annual return between 5%, 8%, and 10% to feel how much a small rate difference compounds over the long run.
Tap 'View yearly growth' to see, year by year, how the value, contributions, and gains pull apart.