Compound Interest Calculator
Calculate compound interest and future value of savings and investments. Free, fast and private.
Formula: A = P(1 + r/n)nt, where A is the future value, P the principal, r the annual rate (as a decimal), n the compounding frequency and t the years. Interest earned = A − P. Results are indicative estimates, not investment advice.
How to use Compound Interest Calculator
- Enter the principal amount, annual interest rate and time in years.
- Choose how often interest compounds — monthly is the most common.
- Click Calculate to see the future value and the interest earned.
Note: this tool runs in your browser. Nothing is uploaded.
Frequently Asked Questions
What is compound interest?
Compound interest is interest earned on both the original principal and the interest already added — so your money grows faster over time than with simple interest.
How is compound interest calculated?
A = P(1 + r/n)^(nt), where P is the principal, r is the annual rate as a decimal, n is how often interest compounds per year, and t is the years.
Does compounding more often earn more?
Yes, slightly. Monthly compounding earns a little more than annual compounding at the same rate, because interest starts earning interest sooner.
Is this compound interest calculator free?
Yes, it is 100% free with no sign-up. Your data stays in your browser.