Compound Interest Calculator
See how savings grow with compound interest over time.
Your future balance appears here
Enter a principal, annual rate, term in years, and how often interest compounds. The final amount and interest earned update live — right here in your browser, with nothing sent to a server.
Runs entirely in your browserProject compound growth, locally
Compound interest is interest earned on both your original money and the interest already added to it, so a balance grows faster the longer it sits. Enter the starting principal, the annual interest rate, the number of years, and how often interest is added each year — monthly, quarterly, or annually. The tool applies A = P(1 + r/m)^(m·t) and shows the final amount alongside the interest earned. Everything runs in your browser and nothing is uploaded.
Common questions
What is the compound interest formula?
The future value is A = P(1 + r/m)^(m·t), where P is the principal, r is the annual rate as a decimal, m is the number of times interest compounds per year, and t is the number of years.
How does compounding frequency affect the result?
The more often interest is added, the more you earn, because each compounding step earns interest on the interest already credited. Monthly compounding beats annual compounding at the same rate.
What is the difference between the final amount and interest earned?
The final amount is your whole balance at the end. The interest earned is that amount minus your original principal — the growth added by compounding.
Does this account for deposits or withdrawals?
No. It models a single lump sum left to grow untouched. Regular contributions or withdrawals would change the result and are not included here.
Are my numbers sent anywhere?
No. The calculation runs entirely in your browser with JavaScript. Nothing you type is uploaded or stored on a server — it is fully client-side and private.