Compound Interest Calculator
See how an investment grows over time with a year-by-year breakdown and chart. Free to use, no signup required for occasional use.
What is the Compound Interest Calculator?
The Compound Interest Calculator shows how an initial sum of money grows over time when interest is earned not just on the original principal, but also on the interest that's already accumulated. Enter your principal (starting amount), the annual interest rate, the number of years, and how often interest compounds (annually, semi-annually, quarterly, monthly, or daily), and the tool calculates your final balance along with the total interest earned. It also produces a simple year-by-year chart so you can visually see how growth accelerates over time — a hallmark of compound interest that's often described as one of the most powerful forces in personal finance. This is useful for evaluating savings accounts, certificates of deposit, bonds, or any interest-bearing investment where you want to understand long-term growth.
How to use it
Enter your principal — the amount you're starting with. Enter the annual interest rate as a percentage. Enter the number of years you plan to let the investment grow. Choose how often interest compounds from the dropdown — more frequent compounding results in slightly higher returns for the same nominal rate. Click 'Calculate' to see your final balance, total interest earned, and a bar chart showing the balance at the end of each year.
Frequently asked questions
Does this include regular monthly contributions?
No, this calculator projects growth of a single lump-sum principal; for a version with ongoing monthly contributions, see the Retirement Savings Calculator.
Why does compounding frequency matter?
More frequent compounding means interest is calculated and added to the balance more often, so subsequent interest is earned on a slightly larger amount sooner, increasing total growth.
What's the difference between compound interest and simple interest?
Simple interest is calculated only on the original principal each period, while compound interest is calculated on the principal plus all previously earned interest.
Is this calculation adjusted for inflation?
No, the result shown is nominal growth; to estimate real purchasing power you'd need to separately adjust for expected inflation.